build(deps): bump the docs group with 2 updates

Bumps the docs group with 2 updates: [mkdocs-include-markdown-plugin](https://github.com/mondeja/mkdocs-include-markdown-plugin) and [mkdocs-material](https://github.com/squidfunk/mkdocs-material).


Updates `mkdocs-include-markdown-plugin` from 7.1.5 to 7.2.0
- [Release notes](https://github.com/mondeja/mkdocs-include-markdown-plugin/releases)
- [Commits](mondeja/mkdocs-include-markdown-plugin@v7.1.5...v7.2.0)

Updates `mkdocs-material` from 9.6.8 to 9.6.21
- [Release notes](https://github.com/squidfunk/mkdocs-material/releases)
- [Changelog](https://github.com/squidfunk/mkdocs-material/blob/master/CHANGELOG)
- [Commits](squidfunk/mkdocs-material@9.6.8...9.6.21)

---
updated-dependencies:
- dependency-name: mkdocs-include-markdown-plugin
  dependency-version: 7.2.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: docs
- dependency-name: mkdocs-material
  dependency-version: 9.6.21
  dependency-type: direct:production
  update-type: version-update:semver-patch
  dependency-group: docs
...

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Author: dependabot[bot]