chore(deps-dev): bump mkdocs-material from 9.1.18 to 9.1.20 (#212)

Bumps [mkdocs-material](https://github.com/squidfunk/mkdocs-material) from 9.1.18 to 9.1.20.
- [Release notes](https://github.com/squidfunk/mkdocs-material/releases)
- [Changelog](https://github.com/squidfunk/mkdocs-material/blob/master/CHANGELOG)
- [Commits](squidfunk/mkdocs-material@9.1.18...9.1.20)

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

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

Author: dependabot[bot]

poetry.lock

@@ -28,7 +28,7 @@ python = "^3.7"
 black = "23.3.0"
 coverage = { extras = ["toml"], version = "7.2.7" }
 mkdocs = "1.4.3"
-mkdocs-material = "9.1.18"
+mkdocs-material = "9.1.20"
 mkdocstrings = { extras = ["python"], version = "0.22.0" }
 mypy = "1.4.1"
 poethepoet = "0.19.0"