Update Workhorse to v8.60.0

Changes:

- Support Git HTTP on toplevel repositories
  https://gitlab.com/gitlab-org/gitlab-workhorse/-/merge_requests/670
- Update GoCloud to v0.21.1+
  https://gitlab.com/gitlab-org/gitlab-workhorse/-/merge_requests/675
- Allow blank S3 regions to be used
  https://gitlab.com/gitlab-org/gitlab-workhorse/-/merge_requests/677

GITLAB_WORKHORSE_VERSION

-8.59.0
+8.60.0

changelogs/unreleased/294007-bump-workhorse.yml

+---
+title: Update Workhorse to v8.60.0
+merge_request: 51965
+author:
+type: changed