Update react monorepo to v19

Author: renovate[bot]

package.json

@@ -17,8 +17,8 @@
     "firebase-admin": "7.2.0",
     "firebase-functions": "2.2.1",
     "next": "8.1.0",
-    "react": "16.8.6",
-    "react-dom": "16.8.6"
+    "react": "19.0.0",
+    "react-dom": "19.0.0"
   },
   "engines": {
     "node": "8"