Upgrade jquery-validation from 1.20.1 to 1.21.0

[snipe]

Just what it says :)

[what-the-diff]

PR Summary

• Update of JQuery-Validation Package
  The jquery-validation package was updated from version 1.20.1 to 1.21.0 in package-lock.json and package.json.

• Changes in JavaScript Files
  The jquery-validation plugin was also updated to 1.21.0 in public/js/build/vendor.js and public/js/dist/all.js. In addition, we introduced the customElements option in the $.extend() function and adjusted the event listeners to integrate custom elements. Lastly, we fine-tuned the regular expressions used for number validation to ensure accurate results.

• Modifications in Mix-Manifest
  In the public/mix-manifest.json file, we made several changes including the addition of a new entry for css/dist/skins/_all-skins.min.css along with a fresh ID. We also refreshed the IDs for js/build/vendor.js and js/dist/all.js.