Queue factories must implement QueueFactoryInterface

Queue factory services must provide a get() method that returns a queue. This was previously not enforced by an interface contract, but you now need to implement \Drupal\Core\Queue\QueueFactoryInterface for your service to work as a queue factory in Drupal 11.

Previous code:

class MyQueueFactory {

  public function get($name) {
    return new MyQueue($name);
  }

}

New code:

use Drupal\Core\Queue\QueueFactoryInterface;

class MyQueueFactory implements QueueFactoryInterface {

  public function get($name) {
    return new MyQueue($name);
  }

}