Bump @docusaurus/theme-mermaid from 3.9.0 to 3.9.1 in /docs

Bumps [@docusaurus/theme-mermaid](https://github.com/facebook/docusaurus/tree/HEAD/packages/docusaurus-theme-mermaid) from 3.9.0 to 3.9.1.
- [Release notes](https://github.com/facebook/docusaurus/releases)
- [Changelog](https://github.com/facebook/docusaurus/blob/main/CHANGELOG.md)
- [Commits](https://github.com/facebook/docusaurus/commits/v3.9.1/packages/docusaurus-theme-mermaid)

---
updated-dependencies:
- dependency-name: "@docusaurus/theme-mermaid"
  dependency-version: 3.9.1
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

docs/package.json

@@ -18,7 +18,7 @@
         "@docusaurus/core": "^3.9.0",
         "@docusaurus/plugin-google-gtag": "^3.9.1",
         "@docusaurus/preset-classic": "^3.9.0",
-        "@docusaurus/theme-mermaid": "^3.9.0",
+        "@docusaurus/theme-mermaid": "^3.9.1",
         "@iconify/react": "^6.0.2",
         "@mdx-js/react": "^3.1.1",
         "clsx": "^2.1.1",