Bump lxml from 4.6.5 to 4.9.1 in /modules/sync

Bumps [lxml](https://github.com/lxml/lxml) from 4.6.5 to 4.9.1.
- [Release notes](https://github.com/lxml/lxml/releases)
- [Changelog](https://github.com/lxml/lxml/blob/master/CHANGES.txt)
- [Commits](https://github.com/lxml/lxml/compare/lxml-4.6.5...lxml-4.9.1)

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

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

modules/sync/requirements.txt

@@ -1,5 +1,5 @@
 cssselect==0.9.2
-lxml==4.6.5
+lxml==4.9.1
 Markdown==2.6.6
 Pillow==9.0.1
 pymongo==3.3.0