ENGCOM-5647: Resolve No validate 'Sort Order' in Widget Form (issue 24154) #24155

 - Merge Pull Request #24155 from edenduong/magento2:2.3-bugfix/validate_sort_order_widget_issue24154
 - Merged commits:
   1. f5e7cfe

Author: magento-engcom-team

app/code/Magento/Widget/Block/Adminhtml/Widget/Instance/Edit/Tab/Main.php

@@ -3,7 +3,7 @@
  * Copyright © Magento, Inc. All rights reserved.
  * See COPYING.txt for license details.
  */
-
+declare(strict_types=1);
 /**
  * Widget Instance Main tab block
  *
@@ -198,7 +198,7 @@ protected function _prepareForm()
                 'name' => 'sort_order',
                 'label' => __('Sort Order'),
                 'title' => __('Sort Order'),
-                'class' => '',
+                'class' => 'validate-number',
                 'required' => false,
                 'note' => __('Sort Order of widget instances in the same container')
             ]