[Snyk] Upgrade @primer/css from 21.3.1 to 21.5.1#2

eternograf wants to merge 2 commits intomaineternograf/docs:mainfrom

snyk-upgrade-bdffda3daa373f87da809bc16f7030a5eternograf/docs:snyk-upgrade-bdffda3daa373f87da809bc16f7030a5Copy head branch name to clipboard