fix name

Author: staroperator

Mathlib/Data/Set/Countable.lean

@@ -361,7 +361,7 @@ theorem uncountable_of_countable_compl [Uncountable α] {s : Set α} (hs : sᶜ.
     s.Uncountable := fun h =>
   Set.uncountable_univ (α := α) (by simpa using hs.union h)
 
-theorem Finite.uncountable_compl [Uncountable α] {s : Set α} (hs : s.Countable) :
+theorem Countable.uncountable_compl [Uncountable α] {s : Set α} (hs : s.Countable) :
     sᶜ.Uncountable := fun h =>
   Set.uncountable_univ (α := α) (by simpa using hs.union h)