Bump mkdocs-material from 9.1.15 to 9.1.19

Bumps [mkdocs-material](https://github.com/squidfunk/mkdocs-material) from 9.1.15 to 9.1.19.
- [Release notes](https://github.com/squidfunk/mkdocs-material/releases)
- [Changelog](https://github.com/squidfunk/mkdocs-material/blob/master/CHANGELOG)
- [Commits](squidfunk/mkdocs-material@9.1.15...9.1.19)

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

Signed-off-by: dependabot[bot] <support@github.com>

requirements.txt

@@ -5,7 +5,7 @@ Markdown ~= 3.3.7
 mkdocs == 1.4.3
 mkdocs-git-revision-date-localized-plugin ~= 1.2.0
 mkdocs-macros-plugin ~= 0.7.0
-mkdocs-material == 9.1.15
+mkdocs-material == 9.1.19
 mkdocs-minify-plugin ~= 0.6.4
 pip-audit == 2.5.6
 Pygments ~= 2.15.1