handle missing ckpt for ysgyolo

    def _load_model(self):

        model_path = self.get_param_value('model path')

        if not osp.exists(model_path):

            global CKPT_LIST

            df_model_path = model_path

            for p in CKPT_LIST:

                if osp.exists(p):

                    df_model_path = p

                    break

            self.logger.warning(f'{model_path} does not exist, try fall back to default value {df_model_path}')

            model_path = df_model_path

        if 'rtdetr' in os.path.basename(model_path):

            from ultralytics import RTDETR as MODEL