Bump pillow from 4.1.1 to 8.2.0

Bumps [pillow](https://github.com/python-pillow/Pillow) from 4.1.1 to 8.2.0.
- [Release notes](https://github.com/python-pillow/Pillow/releases)
- [Changelog](https://github.com/python-pillow/Pillow/blob/master/CHANGES.rst)
- [Commits](python-pillow/Pillow@4.1.1...8.2.0)

---
updated-dependencies:
- dependency-name: pillow
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

requirements-test.txt

@@ -1,5 +1,5 @@
 dj_database_url==0.4.2
 jsonfield==2.0.1
-pillow==4.1.1
+pillow==8.2.0
 psycopg2==2.7.3
 six==1.10.0