⬇️(frontend) react 18.3.1 -> 18.2.0

Downgrade react to 18.2.0.
It seems to have a compatibility issue
with @openfun/cunningham-react.

src/frontend/package.json

@@ -26,6 +26,8 @@
   "resolutions": {
     "@types/node": "20.12.7",
     "@types/react-dom": "18.3.0",
+    "react": "18.2.0",
+    "react-dom": "18.2.0",
     "typescript": "5.4.5"
   }
 }