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

[yaffs-website] / web / core / modules / workflows / tests / modules / workflow_type_test / workflow_type_test.info.yml

name: 'Workflow Type Test'
type: module
description: 'Provides a workflow type plugin for testing.'
package: Testing
version: VERSION
core: 8.x
dependencies:
  - drupal:workflows