Bump pillow from 8.4.0 to 9.1.0

Bumps [pillow](https://github.com/python-pillow/Pillow) from 8.4.0 to 9.1.0.
- [Release notes](https://github.com/python-pillow/Pillow/releases)
- [Changelog](https://github.com/python-pillow/Pillow/blob/main/CHANGES.rst)
- [Commits](python-pillow/Pillow@8.4.0...9.1.0)

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

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

requirements-dev.txt

@@ -12,4 +12,4 @@ pur==5.4.3
 wheel==0.37.1
 setuptools==60.10.0
 twine==3.8.0
-pillow==8.4.0
+pillow==9.1.0