Update whitenoise to 6.3.0

[pyup-bot]

This PR updates whitenoise from 6.2.0 to 6.3.0.

Changelog

6.3.0

------------------

* Add some video file extensions to be ignored during compression.
Since such files are already heavily compressed, further compression rarely helps.

Thanks to Jon Ribbens in `PR 431 <https://github.com/evansd/whitenoise/pull/431>`__.

* Remove the behaviour of decoding byte strings passed for settings that take strings.
This seemed to be left around from supporting Python 2.
This change may be backwards incompatible for a small number of projects.

* Document “hidden” feature of setting ``max_age`` to ``None`` to disable the ``Cache-Control`` header.

* Drop support for working as old-style Django middleware, as support was `removed in Django 2.0 <https://docs.djangoproject.com/en/dev/releases/2.0/#features-removed-in-2-0>`__.

Links

• PyPI: https://pypi.org/project/whitenoise
• Changelog: https://pyup.io/changelogs/whitenoise/
• Repo: https://github.com/evansd/whitenoise