Bump pillow from 6.1.0 to 9.0.1

Bumps [pillow](https://github.com/python-pillow/Pillow) from 6.1.0 to 9.0.1.
- [Release notes](https://github.com/python-pillow/Pillow/releases)
- [Changelog](https://github.com/python-pillow/Pillow/blob/main/CHANGES.rst)
- [Commits](python-pillow/Pillow@6.1.0...9.0.1)

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

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

requirements.txt

@@ -6,5 +6,5 @@ pyaml==19.4.1
 raven==6.10.0
 markdown==3.3.7
 pytest-cov==2.7.1
-pillow==6.1.0
+pillow==9.0.1
 sentry-sdk==0.11.2