return correct type from `EnumType`

activerecord/lib/active_record/enum.rb

@@ -105,6 +105,8 @@ def inherited(base) # :nodoc:
     end
 
     class EnumType < Type::Value # :nodoc:
+      delegate :type, to: :subtype
+
       def initialize(name, mapping, subtype)
         @name = name
         @mapping = mapping

activerecord/test/cases/enum_test.rb

@@ -421,4 +421,8 @@ def self.name; 'Book'; end
     book = Book.new
     assert book.hard?
   end
+
+  test "data type of Enum type" do
+    assert_equal :integer, Book.type_for_attribute('status').type
+  end
 end