pyup: Scheduled weekly dependency update for week 14 (#8071)
* Update django-extensions from 3.1.1 to 3.1.2
* Update regex from 2021.3.17 to 2021.4.4
* Update pillow from 8.1.2 to 8.2.0
* Update pillow from 8.1.2 to 8.2.0
* Update sphinx_rtd_theme from 0.5.1 to 0.5.2
* Update pytest from 6.2.2 to 6.2.3