Bump pillow from 8.3.2 to 9.0.0 in /modules/sync

Bumps [pillow](https://github.com/python-pillow/Pillow) from 8.3.2 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](https://github.com/python-pillow/Pillow/compare/8.3.2...9.0.0)

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

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

modules/sync/requirements.txt

@@ -1,7 +1,7 @@
 cssselect==0.9.2
 lxml==4.6.3
 Markdown==2.6.6
-Pillow==8.3.2
+Pillow==9.0.0
 pymongo==3.3.0
 PyPDF2==1.26.0
 python-frontmatter==0.3.1