[ci skip] Fix missing deprecation in output

Author: nielsdos

ext/standard/tests/serialize/gh19701.phpt

@@ -26,5 +26,6 @@ $data = [clone $baseProduct, $baseProduct];
 echo serialize($data), "\n";
 
 ?>
---EXPECT--
+--EXPECTF--
+Deprecated: The __sleep() serialization magic method has been deprecated. Implement __serialize() instead (or in addition, if support for old PHP versions is necessary) in %s on line %d
 a:2:{i:0;O:4:"Item":2:{s:8:"children";a:1:{i:0;O:4:"Item":2:{s:8:"children";a:0:{}s:6:"parent";O:4:"Item":2:{s:8:"children";a:1:{i:0;r:4;}s:6:"parent";N;}}}s:6:"parent";N;}i:1;r:6;}