chore(package): update cross-env to version 7.0.1

Closes #583

Author: greenkeeper[bot]

package.json

@@ -140,7 +140,7 @@
     "chai": "^4.1.1",
     "clean-webpack-plugin": "^2.0.1",
     "concurrently": "^4.0.1",
-    "cross-env": "^5.1.1",
+    "cross-env": "^7.0.1",
     "css-loader": "^1.0.0",
     "eslint": "^5.2.0",
     "eslint-config-airbnb": "^17.0.0",