Update and configure Webpack Encore

webpack.config.js

@@ -29,9 +29,6 @@ Encore
     .cleanupOutputBeforeBuild()
     .enableBuildNotifications()
     .enableSourceMaps(!Encore.isProduction())
-    .configureBabel((config) => {
-        config.plugins.push('@babel/plugin-proposal-class-properties');
-    })
     .configureBabelPresetEnv((config) => {
         config.useBuiltIns = 'usage';
         config.corejs = 3;