Bump pymdown-extensions from 10.8.1 to 10.9

Bumps [pymdown-extensions](https://github.com/facelessuser/pymdown-extensions) from 10.8.1 to 10.9.
- [Release notes](https://github.com/facelessuser/pymdown-extensions/releases)
- [Commits](facelessuser/pymdown-extensions@10.8.1...10.9)

---
updated-dependencies:
- dependency-name: pymdown-extensions
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

requirements.txt

@@ -3,7 +3,7 @@ mkdocs-git-revision-date-localized-plugin==1.2.6
 mkdocs-macros-plugin==1.0.5
 mkdocs-material==9.5.29
 mkdocs-redirects==1.2.1
-pymdown-extensions==10.8.1
+pymdown-extensions==10.9
 mkdocs-linkcheck==1.0.6
 mdformat-gfm==0.3.6
 mdformat-mkdocs[recommended]==3.0.0