feat(ring_theory/subring): weaken typeclass assumption for `units.pos_subgroup` (#10332)
feat(ring_theory/subring): weaken typeclass assumption for `units.pos_subgroup` (#10332)





Co-authored-by: Eric Wieser <da64e90baec5d084ce3d8e05f3b022ae6d118ff5@gmail.com>

leanprover-community/mathlib,leanprover-community/mathlib