Pin react dev dep so tests pass

Author: mjackson

packages/react-router-native/package.json

@@ -35,7 +35,7 @@
     "babel-jest": "^20.0.3",
     "babel-preset-react-native": "1.9.1",
     "jest": "^20.0.4",
-    "react": "^16.0.0-alpha.6",
+    "react": "16.0.0-alpha.6",
     "react-native": "0.44.0",
     "react-test-renderer": "15.5.4"
   },