[dataset] fix toolbench (local) (#4563)

Author: Jintao-Huang

swift/llm/dataset/loader.py

@@ -243,7 +243,7 @@ def _load_repo_dataset(
             # The dataset downloaded from modelscope will have an additional dataset_infos.json file.
             dataset_infos_path = os.path.join(dataset_id, 'dataset_infos.json')
             if os.path.isfile(dataset_infos_path):
-                os.rename(dataset_infos_path, f'{dataset_infos_path}.bak')
+                os.rename(dataset_infos_path, f'{dataset_infos_path}_bak')
         elif dataset_id.startswith('/'):
             raise ValueError(f'The local path does not exist, dataset_id: `{dataset_id}`. '
                              f'os.path.exists(dataset_id): {os.path.exists(dataset_id)}')