Bump pip from 21.2.3 to 21.2.4 (PR #3180)

Bumps [pip](https://github.com/pypa/pip) from 21.2.3 to 21.2.4.
<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>21.2.4 (2021-08-12)</h1>
<h2>Bug Fixes</h2>
<ul>
<li>Fix 3.6.0 compatibility in link comparison logic. (<code>[#10280](pypa/pip#10280) &lt;https://github.com/pypa/pip/issues/10280&gt;</code>_)</li>
</ul>
</blockquote>
</details>
<details>
<summary>Commits</summary>
<ul>
<li>See full diff in <a href="https://github.com/pypa/pip/commits">compare view</a></li>
</ul>
</details>
<br />

[![Dependabot compatibility score](https://dependabot-badges.githubapp.com/badges/compatibility_score?dependency-name=pip&package-manager=pip&previous-version=21.2.3&new-version=21.2.4)](https://docs.github.com/en/github/managing-security-vulnerabilities/about-dependabot-security-updates#about-compatibility-scores)

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changelogs/unreleased/3180-dependabot.yml

@@ -0,0 +1,5 @@
+change-type: patch
+description: Bump pip from 21.2.3 to 21.2.4
+destination-branches:
+- master
+sections: {}

requirements.txt

@@ -12,7 +12,7 @@ jinja2==3.0.1
 more-itertools==8.8.0
 netifaces==0.11.0
 packaging==21.0
-pip==21.2.3
+pip==21.2.4
 ply==3.11
 pydantic==1.8.2
 pyformance==0.4