chore(package): update html-webpack-plugin to version 4.2.0

Closes #3

Author: greenkeeper[bot]

package.json

@@ -18,7 +18,7 @@
     "babel-loader": "^8.0.6",
     "clean-webpack-plugin": "^3.0.0",
     "dotenv-webpack": "^1.7.0",
-    "html-webpack-plugin": "^3.2.0",
+    "html-webpack-plugin": "^4.2.0",
     "webpack": "^4.34.0",
     "webpack-bundle-analyzer": "^3.3.2",
     "webpack-cli": "^3.3.4",