fix tqdm_class argument of subclass of tqdm (#3111)

* fix tqdm_class argument of subclass of tqdm

* Apply style fixes

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Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

Author: andyxning

src/huggingface_hub/_snapshot_download.py

@@ -1,6 +1,6 @@
 import os
 from pathlib import Path
-from typing import Dict, Iterable, List, Literal, Optional, Union
+from typing import Dict, Iterable, List, Literal, Optional, Type, Union
 
 import requests
 from tqdm.auto import tqdm as base_tqdm
@@ -44,7 +44,7 @@ def snapshot_download(
     allow_patterns: Optional[Union[List[str], str]] = None,
     ignore_patterns: Optional[Union[List[str], str]] = None,
     max_workers: int = 8,
-    tqdm_class: Optional[base_tqdm] = None,
+    tqdm_class: Optional[Type[base_tqdm]] = None,
     headers: Optional[Dict[str, str]] = None,
     endpoint: Optional[str] = None,
     # Deprecated args