Merge branch 'mr-widget-deploy-border-fix' into 'master'

MR widget deploy heading: Fix border bottom color

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/184142



Merged-by: Scott de Jonge <sdejonge@gitlab.com>
Approved-by: Scott de Jonge <sdejonge@gitlab.com>
Co-authored-by: Sascha Eggenberger <seggenberger@gitlab.com>