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:

enqueue-dev/pkg/gps/GpsProducer.php

Lines 33 to 43 in bb6e759

	public function send(Destination $destination, Message $message): void
	{
	InvalidDestinationException::assertDestinationInstanceOf($destination, GpsTopic::class);
	InvalidMessageException::assertMessageInstanceOf($message, GpsMessage::class);
	/** @var Topic $topic */
	$topic = $this->context->getClient()->topic($destination->getTopicName());
	$topic->publish([
	'data' => json_encode($message),
	]);
	}

In Gps producer there is no way to add attribute keys

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