message: update redis_subscribe.phpt
diff: --TEST--
  swoole_coroutine: redis subscribe
  --SKIPIF--
  -<?php require __DIR__ . "/../include/skipif.inc"; ?>
  +<?php require __DIR__ . "/../include/skipif.inc";
  +if (!class_exists('redis', false)) {
  + exit("SKIP");
  +}
  +?>
  --FILE--
  <?php
  require_once __DIR__ . "/../include/swoole.inc";
  