Bump pip from 21.2.4 to 21.3 in /.github/workflows (#63)

Bumps [pip](https://github.com/pypa/pip) from 21.2.4 to 21.3.
<details>
<summary>Changelog</summary>
<p><em>Sourced from <a href="https://github.com/pypa/pip/blob/main/NEWS.rst">pip's changelog</a>.</em></p>
<blockquote>
<h1>21.3 (2021-10-11)</h1>
<h2>Deprecations and Removals</h2>
<ul>
<li>Improve deprecation warning regarding the copying of source trees when installing from a local directory. (<code>[#10128](pypa/pip#10128) &lt;https://github.com/pypa/pip/issues/10128&gt;</code>_)</li>
<li>Suppress location mismatch warnings when pip is invoked from a Python source
tree, so <code>ensurepip</code> does not emit warnings on CPython <code>make install</code>. (<code>[#10270](pypa/pip#10270) &lt;https://github.com/pypa/pip/issues/10270&gt;</code>_)</li>
<li>On Python 3.10 or later, the installation scheme backend has been changed to use
<code>sysconfig</code>. This is to anticipate the deprecation of <code>distutils</code> in Python
3.10, and its scheduled removal in 3.12. For compatibility considerations, pip
installations running on Python 3.9 or lower will continue to use <code>distutils</code>. (<code>[#10358](pypa/pip#10358) &lt;https://github.com/pypa/pip/issues/10358&gt;</code>_)</li>
<li>Remove the <code>--build-dir</code> option and aliases, one last time. (<code>[#10485](pypa/pip#10485) &lt;https://github.com/pypa/pip/issues/10485&gt;</code>_)</li>
<li>In-tree builds are now the default. <code>--use-feature=in-tree-build</code> is now
ignored. <code>--use-deprecated=out-of-tree-build</code> may be used temporarily to ease
the transition. (<code>[#10495](pypa/pip#10495) &lt;https://github.com/pypa/pip/issues/10495&gt;</code>_)</li>
<li>Un-deprecate source distribution re-installation behaviour. (<code>[#8711](pypa/pip#8711) &lt;https://github.com/pypa/pip/issues/8711&gt;</code>_)</li>
</ul>
<h2>Features</h2>
<ul>
<li>Replace vendored appdirs with platformdirs. (<code>[#10202](pypa/pip#10202) &lt;https://github.com/pypa/pip/issues/10202&gt;</code>_)</li>
<li>Support <code>PEP 610 &lt;https://www.python.org/dev/peps/pep-0610/&gt;</code>_ to detect
editable installs in <code>pip freeze</code> and  <code>pip list</code>. The <code>pip list</code> column output
has a new <code>Editable project location</code> column, and the JSON output has a new
<code>editable_project_location</code> field. (<code>[#10249](pypa/pip#10249) &lt;https://github.com/pypa/pip/issues/10249&gt;</code>_)</li>
<li><code>pip freeze</code> will now always fallback to reporting the editable project
location when it encounters a VCS error while analyzing an editable
requirement. Before, it sometimes reported the requirement as non-editable. (<code>[#10410](pypa/pip#10410) &lt;https://github.com/pypa/pip/issues/10410&gt;</code>_)</li>
<li><code>pip show</code> now sorts <code>Requires</code> and <code>Required-By</code> alphabetically. (<code>[#10422](pypa/pip#10422) &lt;https://github.com/pypa/pip/issues/10422&gt;</code>_)</li>
<li>Do not raise error when there are no files to remove with <code>pip cache purge/remove</code>.
Instead log a warning and continue (to log that we removed 0 files). (<code>[#10459](pypa/pip#10459) &lt;https://github.com/pypa/pip/issues/10459&gt;</code>_)</li>
<li>When backtracking during dependency resolution, prefer the dependencies which are involved in the most recent conflict. This can significantly reduce the amount of backtracking required. (<code>[#10479](pypa/pip#10479) &lt;https://github.com/pypa/pip/issues/10479&gt;</code>_)</li>
<li>Cache requirement objects, to improve performance reducing reparses of requirement strings. (<code>[#10550](pypa/pip#10550) &lt;https://github.com/pypa/pip/issues/10550&gt;</code>_)</li>
<li>Support editable installs for projects that have a <code>pyproject.toml</code> and use a
build backend that supports :pep:<code>660</code>. (<code>[#8212](pypa/pip#8212) &lt;https://github.com/pypa/pip/issues/8212&gt;</code>_)</li>
<li>When a revision is specified in a Git URL, use git's partial clone feature to speed up source retrieval. (<code>[#9086](pypa/pip#9086) &lt;https://github.com/pypa/pip/issues/9086&gt;</code>_)</li>
<li>Add a <code>--debug</code> flag, to enable a mode that doesn't log errors and propagates them to the top level instead. This is primarily to aid with debugging pip's crashes. (<code>[#9349](pypa/pip#9349) &lt;https://github.com/pypa/pip/issues/9349&gt;</code>_)</li>
<li>If a host is explicitly specified as trusted by the user (via the --trusted-host option), cache HTTP responses from it in addition to HTTPS ones. (<code>[#9498](pypa/pip#9498) &lt;https://github.com/pypa/pip/issues/9498&gt;</code>_)</li>
</ul>
<h2>Bug Fixes</h2>
<ul>
<li>Present a better error message, when a <code>file:</code> URL is not found. (<code>[#10263](pypa/pip#10263) &lt;https://github.com/pypa/pip/issues/10263&gt;</code>_)</li>
<li>Fix the auth credential cache to allow for the case in which
the index url contains the username, but the password comes
from an external source, such as keyring. (<code>[#10269](pypa/pip#10269) &lt;https://github.com/pypa/pip/issues/10269&gt;</code>_)</li>
<li>Fix double unescape of HTML <code>data-requires-python</code> and <code>data-yanked</code> attributes. (<code>[#10378](pypa/pip#10378) &lt;https://github.com/pypa/pip/issues/10378&gt;</code>_)</li>
<li>New resolver: Fixes depth ordering of packages during resolution, e.g. a dependency 2 levels deep will be ordered before a dependecy 3 levels deep. (<code>[#10482](pypa/pip#10482) &lt;https://github.com/pypa/pip/issues/10482&gt;</code>_)</li>
</ul>
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</blockquote>
<p>... (truncated)</p>
</details>
<details>
<summary>Commits</summary>
<ul>
<li><a href="https://github.com/pypa/pip/commit/abec8a701bfa66aa15fedf4c898011aa2d95f29e"><code>abec8a7</code></a> Bump for release</li>
<li><a href="https://github.com/pypa/pip/commit/68a70486c9224f9d25be3cbf56c73d8a33c6a713"><code>68a7048</code></a> Update AUTHORS.txt</li>
<li><a href="https://github.com/pypa/pip/commit/9f18a403ca41f4e42fbb89d286b6571a099cb54b"><code>9f18a40</code></a> Merge pull request <a href="https://github-redirect.dependabot.com/pypa/pip/issues/10481">#10481</a> from notatallshaw/prefer_failures</li>
<li><a href="https://github.com/pypa/pip/commit/db496cbce518fa159476695db0cd4f1c1a8ab6f5"><code>db496cb</code></a> Merge pull request <a href="https://github-redirect.dependabot.com/pypa/pip/issues/10563">#10563</a> from pradyunsg/shorter-timeout</li>
<li><a href="https://github.com/pypa/pip/commit/4fac2b90a5d200b46e7b576013bb25f4ebb3f937"><code>4fac2b9</code></a> Merge pull request <a href="https://github-redirect.dependabot.com/pypa/pip/issues/10550">#10550</a> from jbylund/joe/cache_requirement_creation</li>
<li><a href="https://github.com/pypa/pip/commit/786957cf85a641d49b4cfcceef717ef229ac8238"><code>786957c</code></a> Use a shorter timeout, to ensure that this fails more often</li>
<li><a href="https://github.com/pypa/pip/commit/1e3c127d4a938643aca1bbc25e6581493e316476"><code>1e3c127</code></a> Avoid passing <code>.</code> to vendoring</li>
<li><a href="https://github.com/pypa/pip/commit/610424f9f8ad1f99d0a48bf9a53e7a9df4242304"><code>610424f</code></a> Quote &quot;PreferenceInformation&quot; to avoid runtime NameError</li>
<li><a href="https://github.com/pypa/pip/commit/c01b5c6d8a4858cf733408b4b020933f902dda9e"><code>c01b5c6</code></a> Update a test for resolvelib 0.8.0</li>
<li><a href="https://github.com/pypa/pip/commit/394a24eb1a5f9af5da7d4d2452ed5fe952de5db2"><code>394a24e</code></a> Upgrade resolvelib to 0.8.0</li>
<li>Additional commits viewable in <a href="https://github.com/pypa/pip/compare/21.2.4...21.3">compare view</a></li>
</ul>
</details>
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.github/workflows/constraints.txt

@@ -1,4 +1,4 @@
-pip==21.2.4
+pip==21.3
 nox==2021.10.1
 nox-poetry==0.8.6
 poetry==1.1.11