chore(deps): bump next from 15.3.5 to 15.4.8 in /apps/pay-test-exchange

Bumps [next](https://github.com/vercel/next.js) from 15.3.5 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@v15.3.5...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]

apps/pay-test-exchange/package.json

@@ -19,7 +19,7 @@
     "class-variance-authority": "0.7.1",
     "clsx": "2.1.1",
     "lucide-react": "0.525.0",
-    "next": "15.3.6",
+    "next": "15.4.8",
     "next-themes": "0.4.6",
     "react": "19.1.2",
     "react-dom": "19.1.2",