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

Closes #237

Author: greenkeeper[bot]

package.json

@@ -104,7 +104,7 @@
     "codelyzer": "^3.1.2",
     "compression-webpack-plugin": "^1.0.0",
     "copy-webpack-plugin": "^4.0.1",
-    "cross-env": "^5.0.1",
+    "cross-env": "^6.0.2",
     "cross-spawn": "^5.0.1",
     "css-loader": "^0.28.7",
     "cssnano": "^3.10.0",