Update mkdocs-material requirement from ==9.0.* to ==9.1.* (#229)

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/CHANGELOG)
- [Commits](squidfunk/mkdocs-material@9.0.0b1...9.1.15)

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

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

requirements_dev.txt

@@ -2,7 +2,7 @@ pip ==23.1.2
 wget
 bump2version ==1.0.1
 # coverage >=4.5.4
-mkdocs-material ==9.0.*
+mkdocs-material ==9.1.*
 mkdocstrings[python] ==0.21.*
 mknotebooks ==0.7.*
 pytest >=5.3.2