Bump next from 15.2.4 to 15.4.8

Bumps [next](https://github.com/vercel/next.js) from 15.2.4 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@v15.2.4...v15.4.8)

---
updated-dependencies:
- dependency-name: next
  dependency-version: 15.4.8
  dependency-type: direct:production
...

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

Author: dependabot[bot]

package.json

@@ -32,7 +32,7 @@
     "lefthook": "^1.11.5",
     "markdown-it-mermaid": "^0.2.5",
     "mermaid": "^11.7.0",
-    "next": "^15.2.4",
+    "next": "^15.4.8",
     "next-themes": "^0.4.6",
     "postcss": "^8.5.3",
     "postcss-import-url": "^7.2.0",