Merge branch 'renovate-gems/gitlab-glfm-markdown' into 'master'

Update dependency gitlab-glfm-markdown to v0.0.28

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/183467



Merged-by: Brett Walker <bwalker@gitlab.com>
Approved-by: Brett Walker <bwalker@gitlab.com>
Co-authored-by: GitLab Renovate Bot <gitlab-bot@gitlab.com>