Update mkdocs requirement from ~=1.4 to ~=1.5

Updates the requirements on [mkdocs](https://github.com/mkdocs/mkdocs) to permit the latest version.
- [Release notes](https://github.com/mkdocs/mkdocs/releases)
- [Commits](mkdocs/mkdocs@1.4.0...1.5.1)

---
updated-dependencies:
- dependency-name: mkdocs
  dependency-type: direct:production
...

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

requirements_docs.txt

@@ -1,5 +1,5 @@
 mike~=1.1
-mkdocs~=1.4
+mkdocs~=1.5
 mkdocs-awesome-pages-plugin~=2.9
 mkdocs-material~=9.1
 mkdocstrings[python-legacy]~=0.22.0