chore(package): update webpack to version 4.28.0

Author: greenkeeper[bot]

package.json

@@ -92,7 +92,7 @@
     "vue-server-renderer": "^2.5.17",
     "vue-style-loader": "^3.0.1",
     "vue-template-compiler": "^2.5.17",
-    "webpack": "^3.6.0",
+    "webpack": "^4.28.0",
     "webpack-bundle-analyzer": "^2.13.1",
     "webpack-dev-server": "^2.9.1",
     "webpack-merge": "^4.1.4"