Upgrade copy-webpack-plugin

package.json

@@ -35,7 +35,7 @@
     "babel-loader": "^8.0.4",
     "clean-webpack-plugin": "^0.1.19",
     "concurrently": "^3.6.1",
-    "copy-webpack-plugin": "^5.1.1",
+    "copy-webpack-plugin": "^6.0.3",
     "cross-env": "^7.0.0",
     "css-loader": "^2.1.1",
     "enzyme": "^3.7.0",