chore(deps): bump next in /code-examples/protect-page-login/nextjs

Bumps [next](https://github.com/vercel/next.js) from 13.5.4 to 15.1.1.
- [Release notes](https://github.com/vercel/next.js/releases)
- [Changelog](https://github.com/vercel/next.js/blob/canary/release.js)
- [Commits](vercel/next.js@v13.5.4...v15.1.1)

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

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