chore: ignore warning

could be not possible to change the owner.

Signed-off-by: Vitor Mattos <vitor@php.rio>

Author: vitormattos

tests/Unit/TestCase.php

@@ -245,7 +245,7 @@ private function getFullLiresignAppFolder(): string {
 			mkdir($path, 0777, true);
 			$user = fileowner(__FILE__);
 			chown($path, $user);
-			chgrp($path, $user);
+			@chgrp($path, $user);
 		}
 		return realpath($path);
 	}