Add missing use statement

Author: fabpot

Tests/ResolvedFormTypeTest.php

@@ -13,6 +13,7 @@
 
 use PHPUnit\Framework\MockObject\MockObject;
 use PHPUnit\Framework\TestCase;
+use Symfony\Component\Form\Extension\Core\Type\HiddenType;
 use Symfony\Component\Form\Form;
 use Symfony\Component\Form\FormConfigInterface;
 use Symfony\Component\Form\FormTypeExtensionInterface;