Bump pillow from 9.0.1 to 9.3.0 in /doc

Bumps [pillow](https://github.com/python-pillow/Pillow) from 9.0.1 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](python-pillow/Pillow@9.0.1...9.3.0)

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

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

doc/requirements.txt

@@ -23,7 +23,7 @@ packaging==20.9
 parso==0.8.2
 pexpect==4.8.0
 pickleshare==0.7.5
-Pillow==9.0.1
+Pillow==9.3.0
 prompt-toolkit==3.0.18
 ptyprocess==0.7.0
 Pygments==2.8.1