Updated 'next' version to 15.5.7 (#590)

Author: mdroidian

apps/website/package.json

@@ -22,7 +22,7 @@
     "gray-matter": "^4.0.3",
     "lucide-react": "^0.540.0",
     "mdast-util-to-string": "^4.0.0",
-    "next": "^15",
+    "next": "15.5.7",
     "openai": "^4.98.0",
     "react": "catalog:",
     "react-dom": "catalog:",