Make `gem-checker` public
I think there are no good reasons to keep this project private. We could make all existing issues confidential (to avoid having to review them all), make pipelines restricted to members only and then make the project public.
I will manually review all MRs to make sure nothing confidential has been mentioned in there but there aren't too many of them.
WDYT @gitlab-com/gl-security/appsec @gitlab-com/gl-security/product-security-engineering ?