chore(package): update html-webpack-plugin to version 4.0.1

Closes #88

Author: greenkeeper[bot]

Diff for: package.json

@@ -71,7 +71,7 @@
     "extract-text-webpack-plugin": "^3.0.0",
     "file-loader": "^3.0.0",
     "friendly-errors-webpack-plugin": "^1.6.1",
-    "html-webpack-plugin": "^3.2.0",
+    "html-webpack-plugin": "^4.0.1",
     "jest": "^23.6.0",
     "jest-serializer-vue": "^2.0.0",
     "node-notifier": "^5.1.2",