Implemented S3 bucket lifecycle configuration (#2041)

* Implemented S3 bucket lifecycle configuration

* Update CHANGELOG.md

* Update S3ClientTest.php

* Update composer.json

Author: GrahamCampbell

src/Generator/ResponseParser/RestXmlParser.php

@@ -376,6 +376,7 @@ private function parseXmlResponseTimestamp(Shape $shape, string $input, bool $re
         $format = $shape->get('timestampFormat') ?? '';
         switch ($format) {
             case '':
+            case 'iso8601':
                 $body = 'new \DateTimeImmutable((string) INPUT)';
 
                 break;