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

Author: greenkeeper[bot]

package.json

@@ -19,7 +19,7 @@
   "devDependencies": {
     "autoprefixer": "9.7.4",
     "clean-webpack-plugin": "3.0.0",
-    "cross-env": "6.0.3",
+    "cross-env": "7.0.0",
     "css-loader": "3.4.0",
     "mini-css-extract-plugin": "0.9.0",
     "postcss-loader": "3.0.0",