Skip persistent connection test if PHP_ZTS enabled.

Author: SkepticalHippo

tests/Redis/RedisConnectionTest.php

@@ -578,6 +578,10 @@ public function it_runs_raw_command()
      */
     public function it_persists_connection()
     {
+        if (PHP_ZTS) {
+            $this->markTestSkipped('PhpRedis does not support persistent connections with PHP_ZTS enabled.');
+        }
+
         $this->assertEquals(
             'laravel',
             $this->connections()['persistent']->getPersistentID()