Bump mkdocs from 1.1.2 to 1.2.1

Bumps [mkdocs](https://github.com/mkdocs/mkdocs) from 1.1.2 to 1.2.1.
- [Release notes](https://github.com/mkdocs/mkdocs/releases)
- [Commits](https://github.com/mkdocs/mkdocs/compare/1.1.2...1.2.1)

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

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

docs/requirements.txt

@@ -7,6 +7,6 @@ mkdocs-material-extensions==1.0.1
 mkdocs-material==7.1.7
 mkdocs-minify-plugin==0.4.0
 mkdocs-redirects==1.0.3
-mkdocs==1.1.2
+mkdocs==1.2.1
 pygments==2.9.0
 pymdown-extensions==8.2