Replace expect()->false() with verify()->false()

codeception/verify 2.1 removed support for expect()->false() so we need
to replace it with verify()->false().

[MAILPOET-5664]

mailpoet/tests/integration/Cron/Workers/SendingQueue/SendingQueueTest.php

@@ -353,7 +353,7 @@ class SendingQueueTest extends \MailPoetTest {
     // queue no longer exists
     $this->sendingQueueWorker->process();
     $queue = SendingQueue::findOne($this->queue->id);
-    expect($queue)->false();
+    verify($queue)->false();
   }
 
   public function testItPassesExtraParametersToMailerWhenTrackingIsDisabled() {