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

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

name: 'Content Moderation'
type: module
description: 'Provides moderation states for content.'
version: VERSION
core: 8.x
package: Core
configure: entity.workflow.collection
dependencies:
  - drupal:workflows