refactor: remove unneeded webpack copy plugin

webpack.config.js

@@ -1,7 +1,6 @@
 const path = require('path');
 const webpack = require('webpack');
 const MiniCssExtractPlugin = require('mini-css-extract-plugin');
-const CopyPlugin = require('copy-webpack-plugin');
 
 module.exports = {
   entry: './app/assets/javascripts/index.ts',
@@ -12,10 +11,6 @@ module.exports = {
     new webpack.DefinePlugin({
       __VERSION__: JSON.stringify(require('./package.json').version)
     }),
-    new CopyPlugin([
-      { from: 'node_modules/snjs/dist/libsodium.bundle.js', to: '../public/dist/libsodium.bundle.js' },
-      { from: 'node_modules/snjs/dist/vendors~libsodium.bundle.js', to: '../public/dist/vendors~libsodium.bundle.js' },
-    ]),
     new MiniCssExtractPlugin({
       // Options similar to the same options in webpackOptions.output
       filename: './stylesheets/app.css',