Bump mkdocs-material from 9.6.20 to 9.6.21 (#204)

Bumps [mkdocs-material](https://github.com/squidfunk/mkdocs-material) from 9.6.20 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@9.6.20...9.6.21)

---
updated-dependencies:
- dependency-name: mkdocs-material
  dependency-version: 9.6.21
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]

requirements_dev.txt

@@ -4,7 +4,7 @@ pydantic>=2.9.2
 pre-commit>=3.6.1
 python-dotenv>=1.0.1
 ruff~=0.13
-mkdocs-material==9.6.20
+mkdocs-material==9.6.21
 mkdocstrings[python]==0.30.1
 mashumaro>=3.13.1
 orjson>=3.10.12