Update webpack to the latest version 🚀 (#1075)

* chore(package): update webpack to version 4.31.0

* chore(package): update lockfile package-lock.json

Author: greenkeeper[bot]

package-lock.json

@@ -92,7 +92,7 @@
     "sass-loader": "7.1.0",
     "style-loader": "0.23.0",
     "svg-prep": "1.0.4",
-    "webpack": "4.30.0",
+    "webpack": "4.31.0",
     "webpack-cli": "3.3.2"
   },
   "scripts": {