Bump mkdocs from 1.5.0 to 1.5.1

Bumps [mkdocs](https://github.com/mkdocs/mkdocs) from 1.5.0 to 1.5.1.
- [Release notes](https://github.com/mkdocs/mkdocs/releases)
- [Commits](mkdocs/mkdocs@1.5.0...1.5.1)

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

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

doc/requirements.txt

@@ -1,3 +1,3 @@
-mkdocs==1.5.0
+mkdocs==1.5.1
 python-markdown-math
 mkdocs-material