Merge branch 'fix-billing-colors' into 'master'

Fix billing card title colors

Closes #6326

See merge request gitlab-org/gitlab-ee!6563

ee/app/views/shared/billings/_billing_plan.html.haml

-.card{ class: ('current' if current_plan?(plan)) }
-  .card-header.bg-info
+.card.bg-info{ class: ('current' if current_plan?(plan)) }
+  .card-header
     = plan.name
 
   .card-body

ee/changelogs/unreleased/fix-billing-colors.yml

+---
+title: Fix billing card title colors
+merge_request: 6563
+author:
+type: fixed