fix tests by upgrading some deps

Author: slorber

package.json

@@ -62,10 +62,10 @@
     "lint-staged": "^8.1.0",
     "prettier": "^1.8.2",
     "pretty-quick": "^1.8.0",
-    "react": "^16.7.0-alpha.2",
+    "react": "^16.8.0",
     "react-native": "^0.57.7",
     "react-navigation": "^3.11.1",
-    "react-test-renderer": "^16.7.0-alpha.2",
+    "react-test-renderer": "^16.8.0",
     "release-it": "^7.6.1",
     "tslint": "^5.11.0",
     "tslint-config-airbnb": "^5.11.1",