chore: change peer dep for S2 to be 19 only

Author: LFDanLu

packages/@react-spectrum/s2/package.json

@@ -174,8 +174,8 @@
     "react-stately": "^3.42.0"
   },
   "peerDependencies": {
-    "react": "^18.0.0 || ^19.0.0-rc.1",
-    "react-dom": "^18.0.0 || ^19.0.0-rc.1"
+    "react": "^19.0.0-rc.1",
+    "react-dom": "^19.0.0-rc.1"
   },
   "publishConfig": {
     "access": "public"