build(deps): bump react-router and react-router-dom in /frontend

Bumps [react-router](https://github.com/remix-run/react-router/tree/HEAD/packages/react-router) to 7.5.3 and updates ancestor dependency [react-router-dom](https://github.com/remix-run/react-router/tree/HEAD/packages/react-router-dom). These dependencies need to be updated together.


Updates `react-router` from 7.1.1 to 7.5.3
- [Release notes](https://github.com/remix-run/react-router/releases)
- [Changelog](https://github.com/remix-run/react-router/blob/main/packages/react-router/CHANGELOG.md)
- [Commits](https://github.com/remix-run/react-router/commits/react-router@7.5.3/packages/react-router)

Updates `react-router-dom` from 7.1.1 to 7.5.3
- [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@7.5.3/packages/react-router-dom)

---
updated-dependencies:
- dependency-name: react-router
  dependency-version: 7.5.3
  dependency-type: indirect
- dependency-name: react-router-dom
  dependency-version: 7.5.3
  dependency-type: direct:production
...

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

frontend/package.json

@@ -35,7 +35,7 @@
     "react-i18next": "^15.4.0",
     "react-markdown": "^9.0.1",
     "react-redux": "^9.2.0",
-    "react-router-dom": "^7.1.1",
+    "react-router-dom": "^7.6.1",
     "react-syntax-highlighter": "^15.5.0",
     "rehype-katex": "^7.0.1",
     "remark-gfm": "^4.0.0",