Bump mkdocs-mermaid2-plugin from 1.1.1 to 1.2.1 in /docs

Bumps [mkdocs-mermaid2-plugin](https://github.com/fralau/mkdocs-mermaid2-plugin) from 1.1.1 to 1.2.1.
- [Release notes](https://github.com/fralau/mkdocs-mermaid2-plugin/releases)
- [Changelog](https://github.com/fralau/mkdocs-mermaid2-plugin/blob/master/CHANGELOG.md)
- [Commits](fralau/mkdocs-mermaid2-plugin@v1.1.1...v1.2.1)

---
updated-dependencies:
- dependency-name: mkdocs-mermaid2-plugin
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

docs/requirements.txt

@@ -1,4 +1,4 @@
 mkdocs==1.6.1
 mkdocs-include-markdown-plugin==7.0.0
 markdown-callouts==0.4.0
-mkdocs-mermaid2-plugin==1.1.1
+mkdocs-mermaid2-plugin==1.2.1