symfony/console: ^5.0 compatibility

[rppgorecki]

Console actions ready for symfony/console 5.*

Execute command should return int, if not error is thrown:

PHP Fatal error: Uncaught TypeError: Return value of "Humus\Amqp\Console\Command\ShowCommand::execute()" must be of the type int, NULL returned. in /var/www/html/vendor/symfony/console/Command/Command.php:258

[prolic]

@rppgorecki see https://github.com/prolic/HumusAmqp/blob/master/composer.json#L21

Console v5 isn't even allowed as of now. If nothing else breaks, we can try to enable support for v4 and v5 as well, but that should at least be tested first.

[rppgorecki]

@prolic I've updated composer.json - all checks have passed (It's really simple change, but needed if you use newer symfony/console in your project)

[prolic]

Thanks a lot