chore(deps-dev): update mkdocs-material requirement in /gh-pages (#3000)

Updates the requirements on [mkdocs-material](https://github.com/squidfunk/mkdocs-material) to permit the latest version.
- [Release notes](https://github.com/squidfunk/mkdocs-material/releases)
- [Changelog](https://github.com/squidfunk/mkdocs-material/blob/master/docs/changelog.md)
- [Commits](squidfunk/mkdocs-material@7.2.8...7.3.0)

---
updated-dependencies:
- dependency-name: mkdocs-material
  dependency-type: direct:development
...

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

gh-pages/requirements-dev.txt

@@ -1,4 +1,4 @@
 mkdocs~=1.2.2
 mkdocs-awesome-pages-plugin~=2.5.0
-mkdocs-material~=7.2.8
+mkdocs-material~=7.3.0
 mkdocs-git-revision-date-plugin~=0.3.1