Give PHP the absolute import path to Traversable

Otherwise, the check for `instanceof Traversable` would always return false. See https://3v4l.org/YgpKg
This affects setCreationOptions on line 121

Author: TysonAndre

src/ElementFactory.php

@@ -9,6 +9,7 @@
 
 namespace Zend\Form;
 
+use Traversable;
 use Interop\Container\ContainerInterface;
 use Zend\ServiceManager\Exception\InvalidServiceException;
 use Zend\ServiceManager\FactoryInterface;