update reproduction templates to use correct React (vercel#65624)

Our reproduction templates are pinned to `next@canary`. This updates to
use the correct `react` & `react-dom` dependencies since `canary` is
pointed to React 19.

Fixes vercel#65619

Author: ztanner

examples/reproduction-template-pages/package.json

@@ -7,8 +7,8 @@
   },
   "dependencies": {
     "next": "canary",
-    "react": "^18.2.0",
-    "react-dom": "^18.2.0"
+    "react": "19.0.0-beta-4508873393-20240430",
+    "react-dom": "19.0.0-beta-4508873393-20240430"
   },
   "devDependencies": {
     "@types/node": "20.4.5",

examples/reproduction-template/package.json

@@ -7,8 +7,8 @@
   },
   "dependencies": {
     "next": "canary",
-    "react": "^18.2.0",
-    "react-dom": "^18.2.0"
+    "react": "19.0.0-beta-4508873393-20240430",
+    "react-dom": "19.0.0-beta-4508873393-20240430"
   },
   "devDependencies": {
     "@types/node": "20.4.5",