mathlib

63138639 - chore(algebra/algebra/unitization): update `comm_semiring` instance for `unitization` (#16048)

chore(algebra/algebra/unitization): update `comm_semiring` instance for `unitization` (#16048) The `comm_monoid` and `comm_semiring` instances for `unitization` had type class restrictions that were too strong because `non_unital_comm_semiring` didn't exist at the time `unitization` was created. This drops those restrictions.