mathlib3

89ada87c - chore(algebra, data/pnat): refactoring comm_semiring_has_dvd into comm_monoid_has_dvd (#3702)

chore(algebra, data/pnat): refactoring comm_semiring_has_dvd into comm_monoid_has_dvd (#3702) changes the instance comm_semiring_has_dvd to apply to any comm_monoid cleans up the pnat API to use this new definition