fix lint

src/llamafactory/hparams/model_args.py

@@ -1,9 +1,13 @@
 from dataclasses import asdict, dataclass, field
-from typing import Any, Dict, Literal, Optional
+from typing import TYPE_CHECKING, Any, Dict, Literal, Optional, Union
 
 from typing_extensions import Self
 
 
+if TYPE_CHECKING:
+    import torch
+
+
 @dataclass
 class ModelArguments:
     r"""
@@ -194,9 +198,9 @@ class ModelArguments:
     )
 
     def __post_init__(self):
-        self.compute_dtype = None
-        self.device_map = None
-        self.model_max_length = None
+        self.compute_dtype: Optional["torch.dtype"] = None
+        self.device_map: Optional[Union[str, Dict[str, Any]]] = None
+        self.model_max_length: Optional[int] = None
 
         if self.split_special_tokens and self.use_fast_tokenizer:
             raise ValueError("`split_special_tokens` is only supported for slow tokenizers.")