⬆️ upgrade nextra monorepo to v4

Author: renovate[bot]

docs/package.json

@@ -14,8 +14,8 @@
     "next": "^14.0.4",
     "next-sitemap": "^4.2.3",
     "next-themes": "^0.4.0",
-    "nextra": "^2.13.2",
-    "nextra-theme-docs": "^2.13.2",
+    "nextra": "^4.0.0",
+    "nextra-theme-docs": "^4.0.0",
     "prism-react-renderer": "^2.0.0",
     "react": "^18.2.0",
     "react-dom": "^18.2.0",