chore(ring_theory/algebra_tower): generalize `is_scalar_tower.right` (#5224)
chore(ring_theory/algebra_tower): generalize `is_scalar_tower.right` (#5224)

The old instance for `[is_scalar_tower R S S]` assumed
[comm_semiring S]` instead of `[semiring S]`.





leanprover-community/mathlib,leanprover-community/mathlib