Bump pillow from 7.1.0 to 9.3.0

Bumps [pillow](https://github.com/python-pillow/Pillow) from 7.1.0 to 9.3.0.
- [Release notes](https://github.com/python-pillow/Pillow/releases)
- [Changelog](https://github.com/python-pillow/Pillow/blob/main/CHANGES.rst)
- [Commits](https://github.com/python-pillow/Pillow/compare/7.1.0...9.3.0)

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

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

requirements.txt

@@ -1,5 +1,5 @@
 Django==2.2.13
-Pillow==7.1.0
+Pillow==9.3.0
 boto3==1.10.45
 coverage==5.0.3
 django-anymail[mailgun]==7.0.0