Issue #3055194 by catch, mikelutz, longwave, mkalkbrenner, hchonov: [Symfony...

Issue #3055194 by catch, mikelutz, longwave, mkalkbrenner, hchonov: [Symfony 5] The signature of the "Drupal\Component\EventDispatcher\ContainerAwareEventDispatcher::dispatch()" method should be updated to "dispatch($event, string $eventName = null)", not doing so is deprecated since Symfony 4.3