mathlib

c3639e94 - refactor(algebra/monoid_algebra) generalize from group to monoid algebras (#5785)

refactor(algebra/monoid_algebra) generalize from group to monoid algebras (#5785) There was a TODO in the monoid algebra file to generalize three statements from group to monoid algebras. It seemed to be solvable by just changing the assumptions, not the proofs. Co-authored-by: Julian-Kuelshammer <68201724+Julian-Kuelshammer@users.noreply.github.com>