Bump mkdocs from 1.4.3 to 1.5.1

Bumps [mkdocs](https://github.com/mkdocs/mkdocs) from 1.4.3 to 1.5.1.
- [Release notes](https://github.com/mkdocs/mkdocs/releases)
- [Commits](mkdocs/mkdocs@1.4.3...1.5.1)

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

Signed-off-by: dependabot[bot] <[email protected]>

requirements.txt

@@ -1,6 +1,6 @@
 # This file contains the direct dependencies required for building the docs
 # To install them all run 'pip install -r requirements.txt' in the same directory
 
-mkdocs == 1.4.3
+mkdocs == 1.5.1
 mkdocs-material == 9.1.21
 mkdocs-redirects == 1.2.1