Bump mkdocs-material from 9.0.15 to 9.1.1

Bumps [mkdocs-material](https://github.com/squidfunk/mkdocs-material) from 9.0.15 to 9.1.1.
- [Release notes](https://github.com/squidfunk/mkdocs-material/releases)
- [Changelog](https://github.com/squidfunk/mkdocs-material/blob/master/CHANGELOG)
- [Commits](squidfunk/mkdocs-material@9.0.15...9.1.1)

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

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

requirements.txt

@@ -1,4 +1,4 @@
 mkdocs==1.4.2
-mkdocs-material==9.0.15
+mkdocs-material==9.1.1
 pygments==2.14.0
 pymdown-extensions==9.10