clean up dirname() (#4307)

Author: deminy

tests/bootstrap.php

@@ -9,4 +9,4 @@
  * @contact  [email protected]
  * @license  https://github.com/hyperf/hyperf/blob/master/LICENSE
  */
-require_once dirname(dirname(__FILE__)) . '/vendor/autoload.php';
+require_once dirname(__DIR__) . '/vendor/autoload.php';