Fix getting default queue settings

[yaroslav-pohil]

This is follow-up for #197

Problem description
Queue check doesn't work properly when you name your queue other than default.

Problem details
The issue is that in laravel the default queue connection is stored as config('queue.default'), but this package calls config('queue. driver'). As a result, the package cannot find the connection config and selects default queue as one to check:

protected function getDefaultQueue($connection)
{
    return config("queue.connections.{$connection}.queue", 'default');
}

[freekmurze]

Thanks!