Groups inheritance breaks "required" argument option

[alvassin]

import argclass

class BaseGroup(argclass.Group):
    option: int

class ExtendedGroup(BaseGroup):
    pass

class Parser(argclass.Parser):
    example = ExtendedGroup()

# option is no more required in ExtendedGroup
parser = Parser()
parser.parse_args()

# AttributeError: Attribute 'option' was not parsed
print(parser.example.option)