chore(deps): update dependency webpack to v4

Author: renovate-bot

demos/vue/ecommerce/package.json

@@ -20,7 +20,7 @@
     "file-loader": "1.1.11",
     "vue-loader": "15.2.6",
     "vue-template-compiler": "2.5.16",
-    "webpack": "3.12.0",
+    "webpack": "4.16.5",
     "webpack-dev-server": "2.11.2"
   }
 }