Bump react-router-dom from 6.26.0 to 7.6.1 in /frontend

Bumps [react-router-dom](https://github.com/remix-run/react-router/tree/HEAD/packages/react-router-dom) from 6.26.0 to 7.6.1.
- [Release notes](https://github.com/remix-run/react-router/releases)
- [Changelog](https://github.com/remix-run/react-router/blob/main/packages/react-router-dom/CHANGELOG.md)
- [Commits](https://github.com/remix-run/react-router/commits/react-router-dom@7.6.1/packages/react-router-dom)

---
updated-dependencies:
- dependency-name: react-router-dom
  dependency-version: 7.6.1
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

frontend/package.json

@@ -34,7 +34,7 @@
     "react-icons": "^5.5.0",
     "react-markdown": "^10.1.0",
     "react-router": "^6.23.1",
-    "react-router-dom": "^6.23.1",
+    "react-router-dom": "^7.6.1",
     "rehype-raw": "^7.0.0",
     "remark-gfm": "^4.0.1",
     "uuid": "^11.1.0"