Enable Merge request approval rules

To improve quality (and security) in Debian I'd like to see Salsa hosted projects adopt a two-approvers-for-each-merge-request rule. GitLab has this feature to allow it: https://docs.gitlab.com/ee/user/project/merge_requests/approvals/rules.html

Unfortunately this is restricted to their Premium and Ultimate tiers.

I don't expect Salsa admins to solve this any soon, but I am posting this issue here for tracking and discussion purposes. Perhaps there is some workaround that can be invented to implement two-person-rule approvals in Salsa despite not having the Premium version of GitLab.