chore(package): update webpack to version 4.28.0

Author: greenkeeper[bot]

package.json

@@ -40,7 +40,7 @@
     "stylelint-order": "2.0.0",
     "stylelint-scss": "3.4.1",
     "stylelint-webpack-plugin": "0.10.5",
-    "webpack": "4.27.1",
+    "webpack": "4.28.0",
     "webpack-cli": "3.1.2"
   },
   "browserslist": [