revert the annotation not supported by old pythons

model_path = os.path.abspath(os.path.join(models_path, model_dir))

model_name = "sd-v1-4.ckpt"

model_url = "https://drive.yerf.org/wl/?id=EBfTrmcCCUAGaQBXVIj5lJmEhjoP1tgl&mode=grid&download=1"

user_dir: (str | None) = None

user_dir = None

CheckpointInfo = namedtuple("CheckpointInfo", ['filename', 'title', 'hash', 'model_name'])

checkpoints_list = {}