chore(deps): bump next from 15.1.2 to 15.2.3

Bumps [next](https://github.com/vercel/next.js) from 15.1.2 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@v15.1.2...v15.2.3)

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

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

Author: dependabot[bot]

examples/next/package.json

@@ -17,7 +17,7 @@
     "@mdx-js/react": "^2.3.0",
     "@next/mdx": "^14.0.4",
     "@theme-ui/css": "workspace:^",
-    "next": "^15.1.2",
+    "next": "^15.2.3",
     "react": "^18.1.0",
     "react-dom": "^18",
     "theme-ui": "workspace:^"