message: update: change plugin for CSS ExtractTextPlugin to MiniCssExtractPlugin
  Because ExtractTextPlugin became deprecated from webpack v4
diff: @@ -6,7 +6,7 @@ const webpack = require("webpack");
  const HtmlPlugin = require("html-webpack-plugin");
  const CopyPlugin = require("copy-webpack-plugin");
  const HtmlIncludeAssetsPlugin = require("html-webpack-include-assets-plugin");
  -const ExtractTextPlugin = require("extract-text-webpack-plugin");
  +const MiniCssExtractPlugin = require("mini-css-extract-plugin");
  const OptimizeCssAssetsPlugin = require("optimize-css-assets-webpack-plugin");
  module.exports = (env, args) => {
  @@ -48,9 +48,11 @@ module.exports = (env, args) => {
  {
  test: /\.css$/,
  use: prod
  - ? ExtractTextPlugin.extract({
  - fallback: "style-loader",
  - use: {
  + ? [
  + {
  + loader: MiniCssExtractPlugin.loader,
  + },
  + {
  loader: "css-loader",
  options: {
  camelCase: true,
  @@ -60,7 +62,7 @@ module.exports = (env, args) => {
  sourceMaps: !prod,
  },
  },
  - })
  + ]
  : [
  "style-loader",
  {
  @@ -115,7 +117,7 @@ module.exports = (env, args) => {
  }),
  ].concat(
  prod
  - ? [new ExtractTextPlugin("style.css"), new OptimizeCssAssetsPlugin()]
  + ? [new MiniCssExtractPlugin("style.css"), new OptimizeCssAssetsPlugin()]
  : [new webpack.HotModuleReplacementPlugin()],
  ),
  resolve: {
  