Fix box-shadow colors in Tailwind

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/149843



Merged-by: Lukas 'ai-pi' Eipert <leipert@gitlab.com>
Approved-by: Lukas 'ai-pi' Eipert <leipert@gitlab.com>
Co-authored-by: Paul Gascou-Vaillancourt <paul.gascvail@gmail.com>