chore(package): update cross-env to version 5.2.0

Author: greenkeeper[bot]

package.json

@@ -28,7 +28,7 @@
     "autoprefixer": "8.6.0",
     "clean-webpack-plugin": "0.1.19",
     "copy-webpack-plugin": "4.5.1",
-    "cross-env": "5.1.6",
+    "cross-env": "5.2.0",
     "css-loader": "0.28.11",
     "file-loader": "1.1.11",
     "mini-css-extract-plugin": "0.4.0",