Fix tests expecting a valid date

Author: stof

Tests/Extension/Core/Type/DateTypeTest.php

@@ -598,7 +598,7 @@ public function testIsSynchronizedReturnsTrueIfChoiceAndCompletelyFilled()
         ));
 
         $form->submit(array(
-            'day' => '0',
+            'day' => '1',
             'month' => '6',
             'year' => '2010',
         ));