chore(Data/Setoid/Basic): abbrev kerLift -> def kerLift

Author: SnirBroshi

Mathlib/Data/Setoid/Basic.lean

@@ -317,7 +317,7 @@ theorem lift_unique {r : Setoid α} {f : α → β} (H : r ≤ ker f) (g : Quoti
   rw [← Quotient.mk, Quotient.lift_mk f H, Hg, Function.comp_apply, Quotient.mk''_eq_mk]
 
 /-- Given a function `f`, lift it to the quotient by its kernel. -/
-abbrev kerLift (f : α → β) : Quotient (ker f) → β := Quotient.lift f fun _ _ => id
+def kerLift (f : α → β) : Quotient (ker f) → β := Quotient.lift f fun _ _ => id
 
 @[simp]
 theorem kerLift_mk (f : α → β) (x : α) : kerLift f ⟦x⟧ = f x := rfl