fix(package): update webpack to version 4.9.2

Closes #33

Author: greenkeeper[bot]

package.json

@@ -28,7 +28,7 @@
     "tmp": "0.0.33",
     "uglifyjs-webpack-plugin": "^1.0.0-beta.3",
     "uuid": "^3.0.1",
-    "webpack": "^3.8.1",
+    "webpack": "^4.9.2",
     "yeoman-environment": "^2.0.5"
   },
   "devDependencies": {