Fix doc tag.

src/Database/Type/DecimalType.php

@@ -9,7 +9,7 @@
  *
  * @copyright     Copyright (c) Cake Software Foundation, Inc. (http://cakefoundation.org)
  * @link          http://cakephp.org CakePHP(tm) Project
- * @since         3.0.0
+ * @since         3.3.4
  * @license       http://www.opensource.org/licenses/mit-license.php MIT License
  */
 namespace Cake\Database\Type;