onRun task not working in this plugin

hey I got this CrossOnlineCount plugin and when I run it I get this error:

Code:

Fatal error: Declaration of jasonwynn10\CrossOnlineCount\UpdateTask::onRun(int $currentTick) must be compatible with pocketmine\scheduler\Task::onRun($currentTick) in C:\Users\Admin\Creative Cloud Files\Desktop\PymePE\OP Duels - PrymePE\plugins\CrossOnlineCount-master\src\jasonwynn10\CrossOnlineCount\UpdateTask.php on line 0
[21:38:09] [Server thread/EMERGENCY]: An unrecoverable error has occurred and the server has crashed. Creating a crash dump

This is the UpdateTask file in the plugin:

PHP:

<?php
namespace jasonwynn10\CrossOnlineCount;

use pocketmine\scheduler\PluginTask;

class UpdateTask extends PluginTask {
    public function onRun(int $currentTick) {
        $this->getOwner()->update();
    }
}

How can I fix this?

 

You are using an outdated version of PocketMine. Download the latest one from here: https://jenkins.pmmp.io/... or make your plugin compatible with the build you are on.