Bump mkdocs from 1.4.2 to 1.5.3 (#179)

Bumps [mkdocs](https://github.com/mkdocs/mkdocs) from 1.4.2 to 1.5.3.
- [Release notes](https://github.com/mkdocs/mkdocs/releases)
- [Commits](https://github.com/mkdocs/mkdocs/compare/1.4.2...1.5.3)

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

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

requirements-docs.txt

@@ -1,4 +1,4 @@
-mkdocs==1.4.2
+mkdocs==1.5.3
 mkdocs-material==9.4.6
 pymdown-extensions==10.3.1
 mike==1.1.2