Bump mkdocs-material from 9.2.8 to 9.3.1

Bumps [mkdocs-material](https://github.com/squidfunk/mkdocs-material) from 9.2.8 to 9.3.1.
- [Release notes](https://github.com/squidfunk/mkdocs-material/releases)
- [Changelog](https://github.com/squidfunk/mkdocs-material/blob/master/CHANGELOG)
- [Commits](https://github.com/squidfunk/mkdocs-material/compare/9.2.8...9.3.1)

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

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

docs/requirements-docs.txt

@@ -1,6 +1,6 @@
 markdown==3.4.4
 mkdocs==1.5.2
-mkdocs-material==9.2.8
+mkdocs-material==9.3.1
 mdx_truly_sane_lists==1.3
 pymdown-extensions==10.3
 jinja2==3.1.2