Bump next from 14.2.4 to 14.2.21 in /frontend

Bumps [next](https://github.com/vercel/next.js) from 14.2.4 to 14.2.21.
- [Release notes](https://github.com/vercel/next.js/releases)
- [Changelog](https://github.com/vercel/next.js/blob/canary/release.js)
- [Commits](vercel/next.js@v14.2.4...v14.2.21)

---
updated-dependencies:
- dependency-name: next
  dependency-type: direct:production
...

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

Author: dependabot[bot]

frontend/package-lock.json

@@ -12,7 +12,7 @@
     "i18next": "^21.8.13",
     "js-yaml": "^4.1.0",
     "lodash": "^4.17.21",
-    "next": "^14.1.1",
+    "next": "^14.2.21",
     "next-transpile-modules": "^10.0.1",
     "react": "^18.2.0",
     "react-dom": "^18.2.0",