override/classes/Validate.php

<?php
//prestashop
//override/classes/Validate.php
class Validate extends ValidateCore {

  public static function isStateIsoCode($iso_code)
    {
        return preg_match('/^[a-zA-Z0-9]{1,4}((-)[a-zA-Z0-9]{1,20})?$/', $iso_code);
    }

}