Fix `prod` command

package.json

@@ -15,6 +15,6 @@
   "scripts": {
     "dev": "NODE_ENV=development node_modules/webpack/bin/webpack.js --progress --config=node_modules/laravel-mix/setup/webpack.config.js",
     "watch": "NODE_ENV=development node_modules/webpack/bin/webpack.js --watch --progress --config=node_modules/laravel-mix/setup/webpack.config.js",
-    "prod": "NODE_ENV=production node_modules/webpack/bin/webpack.js --progress --config=node_modules/laravel-mix/setup/webpack.config.js"
+    "prod": "NODE_ENV=production node_modules/webpack/bin/webpack.js --progress --config=node_modules/laravel-mix/setup/webpack.config.js && grunt"
   }
 }