Update cross-env to the latest version 🚀 (#4780)

* chore(package): update cross-env to version 5.1.6

* chore(package): update lockfile

https://npm.im/greenkeeper-lockfile

Author: greenkeeper[bot]

package-lock.json

@@ -53,7 +53,7 @@
     "babel-plugin-transform-object-rest-spread": "^6.26.0",
     "babel-preset-env": "1.6.1",
     "bcrypt-nodejs": "0.0.3",
-    "cross-env": "5.1.5",
+    "cross-env": "5.1.6",
     "deep-diff": "1.0.1",
     "eslint": "^4.9.0",
     "eslint-plugin-flowtype": "^2.39.1",