Bump mkdocs-material from 8.1.8 to 8.1.9
Bumps [mkdocs-material](https://github.com/squidfunk/mkdocs-material) from 8.1.8 to 8.1.9.
- [Release notes](https://github.com/squidfunk/mkdocs-material/releases)
- [Changelog](https://github.com/squidfunk/mkdocs-material/blob/master/CHANGELOG)
- [Commits](https://github.com/squidfunk/mkdocs-material/compare/8.1.8...8.1.9)
---
updated-dependencies:
- dependency-name: mkdocs-material
dependency-type: direct:development
update-type: version-update:semver-patch
...
Signed-off-by: dependabot[bot] <support@github.com>