chore(package): update cross-env to version 7.0.0

Author: greenkeeper[bot]

package.json

@@ -28,7 +28,7 @@
     "autoprefixer": "9.7.4",
     "clean-webpack-plugin": "3.0.0",
     "copy-webpack-plugin": "5.1.1",
-    "cross-env": "6.0.3",
+    "cross-env": "7.0.0",
     "css-loader": "3.4.0",
     "file-loader": "5.0.2",
     "mini-css-extract-plugin": "0.9.0",