Update django-storages to 1.6.3

[pyup-bot]

There's a new version of django-storages available.
You are currently using 1.6.1. I have updated it to 1.6.3

These links might come in handy: PyPI | Changelog | Repo

Changelog

1.6.3

---

• Revert default AWS_S3_SIGNATURE_VERSION to be V2 to restore backwards
  compatability in S3Boto3. It's recommended that all new projects set
  this to be 's3v4'. (344_)

.. _344: jschneier/django-storages#344

1.6.2

---

• Fix regression in safe_join() to handle a trailing slash in an
  intermediate path. (341_)
• Fix regression in gs.GSBotoStorage got an unespected kwarg.
  (342_)

.. _341: jschneier/django-storages#341
.. _342: jschneier/django-storages#342

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

Happy merging! 🤖