chore(package): update copy-webpack-plugin to version 5.0.4

Closes #130

Author: greenkeeper[bot]

package.json

@@ -76,7 +76,7 @@
     "babel-preset-stage-0": "^6.24.1",
     "bundlesize": "^0.17.0",
     "concurrently": "^4.0.0",
-    "copy-webpack-plugin": "^4.0.1",
+    "copy-webpack-plugin": "^5.0.4",
     "cross-env": "^5.1.4",
     "cross-spawn": "^6.0.5",
     "css-loader": "^1.0.0",