Bump pillow from 6.1.0 to 9.0.0

Bumps [pillow](https://github.com/python-pillow/Pillow) from 6.1.0 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](python-pillow/Pillow@6.1.0...9.0.0)

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

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

Author: dependabot[bot]

requirements.txt

@@ -7,4 +7,4 @@ Cython
 scipy
 six
 scikit-image
-Pillow==6.1.0 
+Pillow==9.0.0