chore(deps): bump next in /examples/nextjs/app-router

Bumps [next](https://github.com/vercel/next.js) from 15.2.2 to 15.2.3.
- [Release notes](https://github.com/vercel/next.js/releases)
- [Changelog](https://github.com/vercel/next.js/blob/canary/release.js)
- [Commits](vercel/next.js@v15.2.2...v15.2.3)

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

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

Author: dependabot[bot]

examples/nextjs/app-router/package-lock.json

@@ -11,7 +11,7 @@
   "dependencies": {
     "@flipt-io/flipt": "^1.2.0",
     "@flipt-io/flipt-client-react": "^0.1.0",
-    "next": "^15.2.2",
+    "next": "^15.2.3",
     "react": "^18.2.0",
     "react-dom": "^18.2.0",
     "typescript": "^4.9.4",