Release v6

TODO

• Increment VERSION
• Move all CHANGELOG entries from master (unreleased) into a new section matching VERSION
• Merge VERSION and CHANGELOG changes to master with no other changes
• Create a tag on master matching version and push to gitlab-org/ci-cd/accessibility
• Verify release-version succeeds in the tag pipeline
• Open a merge request in GitLab to use the new version
• Close this issue