set QueueInterface $payload parameter type to mixed

[algirdasci]

What was changed

Changed QueueInterface $payload parameter from array to mixed.

Why?

All interface implementations uses mixed payload where providing serializable objects are possible. Using QueueInterface as type, triggers phpstan errors of incompatible types:

Example:

class CallbackService
{
    public function __construct(
        // flow is in-memory roadrunner driver (Spiral\RoadRunnerBridge\Queue\Queue)
        private readonly QueueInterface $flow,
    ) {
    }
    
    public function send(): void
    {
        // CallbackJob is DTO which can be serialized
        $job = new CallbackJob();
    
        // call below will trigger phpstan error:
        // phpstan: Parameter #2 $payload of method Spiral\Queue\QueueInterface::push() expects array, CallbackJob given.
        $this->flow->push(CallbackJob, $job);
    }
}

[roxblnfk]

Expanding the parameter type in the interface is a breaking change for backward compatibility. We cannot accept this change in the current version.

However, we can consider declaring a broader type with annotations.