mathlib3

511a9f79 - feat(algebra/gcd_monoid): GCD domains are integrally closed. (#15109)

feat(algebra/gcd_monoid): GCD domains are integrally closed. (#15109) Co-authored-by: Junyan Xu <junyanxumath@gmail.com> Co-authored-by: Andrew Yang <36414270+erdOne@users.noreply.github.com>