Bump next from 15.4.9 to 16.1.5 in /playground/connect-next

Bumps [next](https://github.com/vercel/next.js) from 15.4.9 to 16.1.5.
- [Release notes](https://github.com/vercel/next.js/releases)
- [Changelog](https://github.com/vercel/next.js/blob/canary/release.js)
- [Commits](vercel/next.js@v15.4.9...v16.1.5)

---
updated-dependencies:
- dependency-name: next
  dependency-version: 16.1.5
  dependency-type: direct:production
...

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

Author: dependabot[bot]

playground/connect-next/package.json

@@ -26,7 +26,7 @@
     "jsonwebtoken": "^9.0.2",
     "jwks-rsa": "^3.1.0",
     "lucide-react": "^0.507.0",
-    "next": "15.4.9",
+    "next": "16.1.5",
     "qrcode.react": "^4.2.0",
     "react": "^18",
     "react-dom": "^18",