chore(package): update jest to version 21.0.1

Closes #37

Author: greenkeeper[bot]

package.json

@@ -36,7 +36,7 @@
     "eslint-plugin-jsx-a11y": "5.1.1",
     "eslint-plugin-react": "7.2.1",
     "flow-bin": "0.52.0",
-    "jest": "20.0.4",
+    "jest": "21.0.1",
     "react-test-renderer": "16.0.0-alpha.12"
   },
   "jest": {