Update dependency next to v13 [SECURITY]

Author: renovate[bot]

site/package.json

@@ -11,7 +11,7 @@
   "dependencies": {
     "classnames": "2.3.1",
     "date-fns": "2.23.0",
-    "next": "11.1.2",
+    "next": "13.5.0",
     "react": "17.0.2",
     "react-datocms": "1.6.3",
     "react-dom": "17.0.2",