Update dependency nuxt to v4

Author: renovate[bot]

packages/site/package.json

@@ -20,7 +20,7 @@
     "markdown-it": "14.1.0",
     "modern-normalize": "3.0.1",
     "nuxi": "3.28.0",
-    "nuxt": "3.19.2",
+    "nuxt": "4.1.3",
     "pinia": "3.0.3",
     "site-config": "1.0.0",
     "twitter-text": "3.1.0"