Minor update to make rank optional in peft class (#846)

Make rank flexible and add some other checks for, eg, lora and fact-based peft methods

Author: anwai98

micro_sam/models/peft_sam.py

@@ -307,15 +307,17 @@ class PEFT_Sam(nn.Module):
     def __init__(
         self,
         model: Sam,
-        rank: int,
+        rank: Optional[int] = None,
         peft_module: nn.Module = LoRASurgery,
         attention_layers_to_update: Union[List[int]] = None,
         quantize: bool = False,
         **module_kwargs
     ):
         super().__init__()
 
-        assert rank > 0
+        if issubclass(peft_module, Union[LoRASurgery, FacTSurgery]) and (not rank or rank <= 0):
+            raise RuntimeError("The chosen PEFT method cannot run without a valid rank choice.")
+
         assert issubclass(peft_module, Union[LoRASurgery, FacTSurgery, SelectiveSurgery, SSFSurgery, AdaptFormer]), (
             "Invalid PEFT module"
         )