Update dependency next to v16 [SECURITY]

Author: renovate[bot]

package.json

@@ -9,7 +9,7 @@
     "postinstall": "fumadocs-mdx"
   },
   "dependencies": {
-    "next": "15.3.1",
+    "next": "16.0.0",
     "react": "^19.1.0",
     "react-dom": "^19.1.0",
     "fumadocs-ui": "15.2.8",