Update whitenoise to 3.2.1

[pyup-bot]

There's a new version of whitenoise available.
You are currently using 2.0.6. I have updated it to 3.2.1

Changelog

3.2.1

---

• Handle non-ASCII URLs correctly when using the wsgi.py integration.
• Fix exception triggered when a static files "finder" returned a directory
  rather than a file.

3.2

---

• Add support for the new-style middleware classes introduced in Django 1.10.
  The same WhiteNoiseMiddleware class can now be used in either the old
  MIDDLEWARE_CLASSES list or the new MIDDLEWARE list.
• Fixed a bug where incorrect Content-Type headers were being sent on 304 Not
  Modified responses (thanks oppianmatt <https://github.com/oppianmatt>_).
• Return Vary and Cache-Control headers on 304 responses, as specified by the
  RFC <http://tools.ietf.org/html/rfc7232section-4.1>_.

3.1

---

• Add new :any:WHITENOISE_STATIC_PREFIX setting to give flexibility in
  supporting non-standard deployment configurations e.g. serving the
  application somewhere other than the domain root.
• Fix bytes/unicode bug when running with Django 1.10 on Python 2.7

3.0

---

.. note:: The latest version of WhiteNoise contains some small breaking changes.
Most users will be able to upgrade without any problems, but some
less-used APIs have been modified:

• The setting WHITENOISE_GZIP_EXCLUDE_EXTENSIONS has been renamed to
  WHITENOISE_SKIP_COMPRESS_EXTENSIONS.
• The CLI :ref:compression utility <cli-utility> has moved from python -m whitenoise.gzip
  to python -m whitenoise.compress.
• The now redundant gzipstatic management command has been removed.
• WhiteNoise no longer uses the system mimetypes files, so if you are serving
  particularly obscure filetypes you may need to add their mimetypes explicitly
  using the new :any:mimetypes <WHITENOISE_MIMETYPES> setting.
• Older versions of Django (1.4-1.7) and Python (2.6) are no longer supported.
  If you need support for these platforms you can continue to use WhiteNoise 2.x_.
• The whitenoise.django.GzipManifestStaticFilesStorage storage backend
  has been moved to
  whitenoise.storage.CompressedManifestStaticFilesStorage. The old
  import path will continue to work for now, but users are encouraged
  to update their code to use the new path.

.. _WhiteNoise 2.x: http://whitenoise.evans.io/en/legacy-2.x/

Simpler, cleaner Django middleware integration
++++++++++++++++++++++++++++++++++++++++++++++

WhiteNoise can now integrate with Django by adding a single line to
MIDDLEWARE_CLASSES without any need to edit wsgi.py. This also means
that WhiteNoise plays nicely with other middleware classes such as
SecurityMiddleware, and that it is fully compatible with the new Channels_
system. See the :ref:updated documentation <django-middleware> for details.

.. _Channels: https://channels.readthedocs.org/en/latest/

Brotli compression support
++++++++++++++++++++++++++

Brotli_ is the modern, more efficient alternative to gzip for HTTP
compression. To benefit from smaller files and faster page loads, just install
the brotlipy_ library, update your requirements.txt and WhiteNoise
will take care of the rest. See the :ref:documentation <brotli-compression>
for details.

.. _brotli: https://en.wikipedia.org/wiki/Brotli
.. _brotlipy: http://brotlipy.readthedocs.org/en/latest/

Simpler customisation
+++++++++++++++++++++

It's now possibe to add custom headers to WhiteNoise without needing to create
a subclass, using the new :any:add_headers_function <WHITENOISE_ADD_HEADERS_FUNCTION> setting.

Use WhiteNoise in development with Django
+++++++++++++++++++++++++++++++++++++++++

There's now an option to force Django to use WhiteNoise in development, rather
than its own static file handling. This results in more consistent behaviour
between development and production environments and fewer opportunities for
bugs and surprises. See the :ref:documentation <runserver-nostatic> for
details.

Improved mimetype handling
++++++++++++++++++++++++++

WhiteNoise now ships with its own mimetype definitions (based on those shipped
with nginx) instead of relying on the system ones, which can vary between
environments. There is a new :any:mimetypes <WHITENOISE_MIMETYPES>
configuration option which makes it easy to add additional type definitions if
needed.

Thanks
++++++

A big thank-you to Ed Morley <https://github.com/edmorley>_ and Tim Graham <https://github.com/timgraham>_ for their contributions to this release.

Got merge conflicts? Close this PR and delete the branch. I'll create a new PR for you.

Happy merging! 🤖