refactor: remove deprecated jQuery .ready() syntax (#2738)

jQuery 3 recommends `$( handler )` syntax.

Reference: https://api.jquery.com/ready/

resources/scripts/app.js

@@ -3,6 +3,6 @@
  */
 import 'jquery';
 
-$(document).ready(() => {
+$(() => {
   // console.log('Hello world');
 });