MNT: (deps): Bump pillow from 8.1.2 to 8.2.0 in /ci

Bumps [pillow](https://github.com/python-pillow/Pillow) from 8.1.2 to 8.2.0.
- [Release notes](https://github.com/python-pillow/Pillow/releases)
- [Changelog](https://github.com/python-pillow/Pillow/blob/master/CHANGES.rst)
- [Commits](python-pillow/Pillow@8.1.2...8.2.0)

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

ci/doc_requirements.txt

@@ -6,4 +6,4 @@ sphinx-gallery==0.9.0
 myst-parser==0.14.0
 netCDF4==1.5.6
 # Needed for sphinx-gallery, which refuses to list dependencies
-pillow==8.1.2
+pillow==8.2.0