Using a real Timer instance, since pre-historic PHPUnit versions are being used in CI

Author: Ocramius

tests/Timer/TimersTest.php

@@ -30,10 +30,8 @@ public function testContains()
     {
         $timers = new Timers();
 
-        /** @var TimerInterface $timer1 */
-        $timer1 = $this->createMock('React\EventLoop\TimerInterface');
-        /** @var TimerInterface $timer2 */
-        $timer2 = $this->createMock('React\EventLoop\TimerInterface');
+        $timer1 = new Timer(0.1, function () {});
+        $timer2 = new Timer(0.1, function () {});
 
         $timers->add($timer1);