Update pytest-django to 3.4.6

[pyup-bot]

This PR updates pytest-django from 3.4.5 to 3.4.6.

Changelog

3.4.6

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

Bugfixes
^^^^^^^^

* django_find_project: add cwd as fallback always (690)

Misc
^^^^

* Enable tests for Django 2.2 and add classifier (693)
* Disallow pytest 4.2.0 in ``install_requires`` (697)

Links

• PyPI: https://pypi.org/project/pytest-django
• Changelog: https://pyup.io/changelogs/pytest-django/
• Docs: https://pytest-django.readthedocs.io/

[pyup-bot]

Closing this in favor of #569