Bump mkdocs-material from 9.1.8 to 9.1.9

Bumps [mkdocs-material](https://github.com/squidfunk/mkdocs-material) from 9.1.8 to 9.1.9.
- [Release notes](https://github.com/squidfunk/mkdocs-material/releases)
- [Changelog](https://github.com/squidfunk/mkdocs-material/blob/master/CHANGELOG)
- [Commits](squidfunk/mkdocs-material@9.1.8...9.1.9)

---
updated-dependencies:
- dependency-name: mkdocs-material
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]

requirements.txt

@@ -1,4 +1,4 @@
 mkdocs==1.4.2
-mkdocs-material==9.1.8
+mkdocs-material==9.1.9
 pygments==2.15.1
 pymdown-extensions==9.11