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

[yaffs-website] / web / core / modules / content_translation / tests / modules / content_translation_test / content_translation_test.info.yml

name: 'Content translation tests'
type: module
description: 'Provides content translation tests.'
package: Testing
version: VERSION
core: 8.x
dependencies:
  - drupal:content_translation
  - drupal:language
  - drupal:entity_test