chore(algebra/category/CommRing/limits): avoid `is_ring_hom` (#2142)
chore(algebra/category/CommRing/limits): avoid `is_ring_hom` (#2142)

define a `ring_hom` instead

Co-authored-by: mergify[bot] <b09a6ee808b67e98a221404e7aaa52e0398a4954@users.noreply.github.com>
leanprover-community/mathlib,leanprover-community/mathlib