Remove invalid datetime in test

closes #837

Author: matason

tests/Constraints/FormatTest.php

@@ -105,7 +105,6 @@ public function getValidFormats(): \Generator
         yield [4.2, 'time'];
 
         yield ['2000-05-01T12:12:12Z', 'date-time'];
-        yield ['2000-05-01T12:12:12+0100', 'date-time'];
         yield ['2000-05-01T12:12:12+01:00', 'date-time'];
         yield ['2000-05-01T12:12:12.123456Z', 'date-time'];
         yield ['2000-05-01T12:12:12.123Z', 'date-time'];