Bump mkdocs from 1.5.3 to 1.6.0

Bumps [mkdocs](https://github.com/mkdocs/mkdocs) from 1.5.3 to 1.6.0.
- [Release notes](https://github.com/mkdocs/mkdocs/releases)
- [Commits](mkdocs/mkdocs@1.5.3...1.6.0)

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

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

requirements.txt

@@ -9,7 +9,7 @@ lunr==0.7.0.post1
 Markdown==3.6
 markdown-include==0.8.1
 MarkupSafe==2.1.5
-mkdocs==1.5.3
+mkdocs==1.6.0
 mkdocs-cinder==1.2.0
 mkdocs-minify-plugin==0.8.0
 mkdocs-redirects==1.2.1