ExternalIDSerializerField to be UUID Field instead of Field (#1958)

care/utils/serializer/external_id_field.py

@@ -13,7 +13,7 @@ def __call__(self, value):
             raise serializers.ValidationError("invalid uuid")
 
 
-class ExternalIdSerializerField(serializers.Field):
+class ExternalIdSerializerField(serializers.UUIDField):
     def __init__(self, queryset=None, *args, **kwargs):
         super().__init__(*args, **kwargs)
         self.queryset = queryset