Bump mkdocs-material from 7.1.7 to 7.1.8

Bumps [mkdocs-material](https://github.com/squidfunk/mkdocs-material) from 7.1.7 to 7.1.8.
- [Release notes](https://github.com/squidfunk/mkdocs-material/releases)
- [Changelog](https://github.com/squidfunk/mkdocs-material/blob/master/docs/changelog.md)
- [Commits](squidfunk/mkdocs-material@7.1.7...7.1.8)

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

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

requirements.txt

@@ -1,5 +1,5 @@
 pymdown-extensions==8.2
 pygments==2.9.0
-mkdocs-material==7.1.7
+mkdocs-material==7.1.8
 mkdocs==1.2.1
 mkdocs-cluster==0.0.9