refactor: use existing and simpler method

inc/Form/OptGroup.php

@@ -88,9 +88,8 @@ class OptGroup extends Element {
         foreach($this->options as $key => $val) {
             $selected = ($key == $this->value) ? ' selected="selected"' : '';
             $attrs = '';
-            if (is_array($val['attrs'])) {
-                array_walk($val['attrs'],function (&$aval, $akey){$aval = hsc($akey).'="'.hsc($aval).'"';});
-                $attrs = join(' ', $val['attrs']);
+            if (!empty($val['attrs']) && is_array($val['attrs'])) {
+                $attrs = buildAttributes($val['attrs']);
             }
             $html .= '<option' . $selected . ' value="' . hsc($key) . '" '.$attrs.'>' . hsc($val['label']) . '</option>';
         }