chore(deps-dev): bump mkdocs-material from 9.5.49 to 9.6.15

Bumps [mkdocs-material](https://github.com/squidfunk/mkdocs-material) from 9.5.49 to 9.6.15.
- [Release notes](https://github.com/squidfunk/mkdocs-material/releases)
- [Changelog](https://github.com/squidfunk/mkdocs-material/blob/master/CHANGELOG)
- [Commits](squidfunk/mkdocs-material@9.5.49...9.6.15)

---
updated-dependencies:
- dependency-name: mkdocs-material
  dependency-version: 9.6.15
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]