Upgrade demo to Next 11

Co-Authored-By: Adam Wathan <[email protected]>

Author: reinink

Diff for: package.json

@@ -40,11 +40,11 @@
     "dedent": "^0.7.0",
     "highlight.js": "^10.4.1",
     "jest": "^26.6.1",
-    "next": "10",
+    "next": "^11.1.2",
     "postcss": "^8.2.3",
     "prettier": "^2.1.2",
-    "react": "^16.8.6",
-    "react-dom": "^16.8.6",
+    "react": "^17.0.2",
+    "react-dom": "^17.0.2",
     "snapshot-diff": "^0.8.1",
     "tailwindcss": "^2.0.2"
   },