Updated Drupal to 8.6. This goes with the following updates because it's possible...

[yaffs-website] / web / core / modules / content_moderation / content_moderation.links.task.yml

content_moderation.workflows:
  deriver: 'Drupal\content_moderation\Plugin\Derivative\DynamicLocalTasks'
  weight: 100

content_moderation.content:
  title: 'Overview'
  route_name: system.admin_content
  parent_id: system.admin_content

content_moderation.moderated_content:
  title: 'Moderated content'
  route_name: content_moderation.admin_moderated_content
  parent_id: system.admin_content
  weight: 1