chore(package): update cross-env to version 6.0.2

Closes #132

Author: greenkeeper[bot]

package.json

@@ -48,7 +48,7 @@
     "codecov": "^3.1.0",
     "coveralls": "^3.0.2",
     "cpy-cli": "^2.0.0",
-    "cross-env": "^5.2.0",
+    "cross-env": "^6.0.2",
     "css-modules-require-hook": "^4.2.3",
     "eslint": "^5.12.0",
     "eslint-config-airbnb": "17.1.0",