chore(deps): bump next from 15.1.7 to 15.4.8 in /examples/nextjs

Bumps [next](https://github.com/vercel/next.js) from 15.1.7 to 15.4.8.
- [Release notes](https://github.com/vercel/next.js/releases)
- [Changelog](https://github.com/vercel/next.js/blob/canary/release.js)
- [Commits](vercel/next.js@v15.1.7...v15.4.8)

---
updated-dependencies:
- dependency-name: next
  dependency-version: 15.4.8
  dependency-type: direct:production
...

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

Author: dependabot[bot]

examples/nextjs/package.json

@@ -18,7 +18,7 @@
     "@firebase-oss/ui-styles": "workspace:*",
     "@firebase-oss/ui-translations": "workspace:*",
     "firebase": "catalog:",
-    "next": "15.1.7",
+    "next": "15.4.8",
     "react": "catalog:",
     "react-dom": "catalog:",
     "server-only": "^0.0.1"