message: Fix aio test (enable log).
diff: @@ -14,7 +14,7 @@ $pm->childFunc = function () use ($pm) {
  assert(Co::readFile(__FILE__) === __FILE_CONTENTS__); // will be discarded
  });
  $server = new Swoole\Server('127.0.0.1', $pm->getFreePort());
  - $server->set(['worker_num' => 1, 'log_file' => '/dev/null']);
  + $server->set(['worker_num' => 1]);
  $server->on('WorkerStart', function (Swoole\Server $server, int $worker_id) use ($pm) {
  echo 'read file' . PHP_EOL;
  assert(Co::readFile(__FILE__) === __FILE_CONTENTS__);
  