chore(deps): bump mkdocs from 1.3.1 to 1.4.2 in /docs/_build

Bumps [mkdocs](https://github.com/mkdocs/mkdocs) from 1.3.1 to 1.4.2.
- [Release notes](https://github.com/mkdocs/mkdocs/releases)
- [Commits](https://github.com/mkdocs/mkdocs/compare/1.3.1...1.4.2)

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

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

docs/_build/requirements.txt

@@ -6,7 +6,7 @@ Jinja2==3.1.2
 Markdown==3.3.7
 MarkupSafe==2.1.2
 mergedeep==1.3.4
-mkdocs==1.3.1
+mkdocs==1.4.2
 mkdocs-exclude==1.0.2
 mkdocs-material==8.4.2
 mkdocs-material-extensions==1.1.1