chore(package): update jest to version 21.0.0

Author: greenkeeper[bot]

package.json

@@ -39,7 +39,7 @@
     "eslint-plugin-jsx-a11y": "^6.0.0",
     "eslint-plugin-react": "^7.0.1",
     "isomorphic-fetch": "^2.2.1",
-    "jest": "^20.0.1",
+    "jest": "^21.0.0",
     "jest-cli": "^20.0.4",
     "jest-fetch-mock": "^1.1.1"
   },