Add ability to add attribute keys in GPS producer

[mhv666]

Hi, I would like to ask for a Feture Request, to add the ability to add attribute keys when you publish a topic: https://github.com/php-enqueue/enqueue-dev/blob/bb6e75989970795154d64968fe6bd4cd65b424d3/pkg/gps/GpsProducer.php#L33-L43

In Gps producer there is no way to add attribute keys

If I'm not wrong should be something like this: