Remove unecessary required fields count when exclude_none is set (#1708)

Author: Viicos

src/serializers/fields.rs

@@ -162,11 +162,6 @@ impl GeneralFieldsSerializer {
             let key_str = key_str(&key)?;
             let op_field = self.fields.get(key_str);
             if extra.exclude_none && value.is_none() {
-                if let Some(field) = op_field {
-                    if field.required {
-                        used_req_fields += 1;
-                    }
-                }
                 continue;
             }
             let field_extra = Extra {