Bump mkdocs from 1.2.3 to 1.3.1 (#216)

Bumps [mkdocs](https://github.com/mkdocs/mkdocs) from 1.2.3 to 1.3.1.
- [Release notes](https://github.com/mkdocs/mkdocs/releases)
- [Commits](mkdocs/mkdocs@1.2.3...1.3.1)

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

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

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

Author: dependabot[bot]

requirements-docs.txt

@@ -1,2 +1,2 @@
-mkdocs==1.2.3
+mkdocs==1.3.1
 mkdocs-material==8.1.7