deps: update mkdocs requirement from >=1.5.0 to >=1.6.1

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@1.5.0...1.6.1)

---
updated-dependencies:
- dependency-name: mkdocs
  dependency-version: 1.6.1
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

docs-requirements.txt

@@ -2,7 +2,7 @@
 # Install with: pip install -r docs-requirements.txt
 
 # Core MkDocs
-mkdocs>=1.5.0
+mkdocs>=1.6.1
 
 # Material theme
 mkdocs-material>=9.5.0