chore(package): update cross-env to version 6.0.3

Closes #118

Author: greenkeeper[bot]

package.json

@@ -127,7 +127,7 @@
     "asar": "^0.14.0",
     "boiler-room-custodian": "^0.6.2",
     "concurrently": "^3.1.0",
-    "cross-env": "^5.0.1",
+    "cross-env": "^6.0.3",
     "css-loader": "^0.28.4",
     "css-modules-require-hook": "^4.0.6",
     "devtron": "^1.4.0",