Remove unused variable in Core\Worker::defer

src/Core/Worker.php

@@ -1378,8 +1378,9 @@ class Worker
 	 * Defers the current worker entry
 	 *
 	 * @return boolean had the entry been deferred?
+	 * @throws \Exception
 	 */
-	public static function defer()
+	public static function defer(): bool
 	{
 		$queue = DI::app()->getQueue();
 
@@ -1387,7 +1388,6 @@ class Worker
 			return false;
 		}
 
-		$retrial = $queue['retrial'];
 		$id = $queue['id'];
 		$priority = $queue['priority'];