build(deps): bump pymdown-extensions from 10.8.1 to 10.9 in /_build

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>

_build/requirements.txt

@@ -12,7 +12,7 @@ mkdocs-material==9.5.30
 mkdocs-material-extensions==1.3.1
 packaging==24.1
 Pygments==2.18.0
-pymdown-extensions==10.8.1
+pymdown-extensions==10.9
 pyparsing==3.1.2
 python-dateutil==2.9.0.post0
 PyYAML==6.0.1