Bump pillow from 8.4.0 to 9.0.0

Bumps [pillow](https://github.com/python-pillow/Pillow) from 8.4.0 to 9.0.0.
- [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/8.4.0...9.0.0)

---
updated-dependencies:
- dependency-name: pillow
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

requirements.txt

@@ -13,7 +13,7 @@ bleach-allowlist==1.0.3
 gunicorn==20.1.0
 lxml==4.7.1
 Markdown==3.3.6
-Pillow==8.4.0
+Pillow==9.0.0
 psycopg2-binary==2.9.3
 python-dotenv==0.19.2
 requests==2.26.0