chore(deps): bump next from 14.2.26 to 15.2.4

Bumps [next](https://github.com/vercel/next.js) from 14.2.26 to 15.2.4.
- [Release notes](https://github.com/vercel/next.js/releases)
- [Changelog](https://github.com/vercel/next.js/blob/canary/release.js)
- [Commits](vercel/next.js@v14.2.26...v15.2.4)

---
updated-dependencies:
- dependency-name: next
  dependency-version: 15.2.4
  dependency-type: direct:production
...

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

Author: dependabot[bot]

examples/theming/package.json

@@ -13,7 +13,7 @@
     "@primer/octicons-react": "^19.14.0",
     "@primer/react": "37.25.0",
     "clsx": "^2.1.1",
-    "next": "^14.2.26",
+    "next": "^15.2.4",
     "react": "^18.3.1",
     "react-dom": "^18.3.1",
     "styled-components": "5.x",