Missing filehash parameter

Hi,

The change is necessary in order to fix this (when extending from WhatsAppEventListenerBase):

Fatal error: Declaration of WhatsAppEventListenerBase::onMediaMessageSent() must be compatible with WhatsAppEventListener::onMediaMessageSent($phone, $to, $id, $filetype, $url, $filename, $filesize, $filehash, $icon) in ../WhatsAPI/src/events/WhatsAppEventListenerBase.php on line 19