Fix DDC767Test failing on php7 + pg94

The failure happens when running the full suite or even just:

phpunit tests/Doctrine/Tests/ORM/Functional/Ticket

tests/Doctrine/Tests/ORM/Functional/Ticket/DDC767Test.php

@@ -49,7 +49,7 @@ class DDC767Test extends \Doctrine\Tests\OrmFunctionalTestCase
 
         $this->assertNotNull($pUser, "User not retrieved from database.");
 
-        $groups = array(2, 3);
+        $groups = array($group2->id, $group3->id);
 
         try {
             $this->_em->beginTransaction();