[Major] Support deleting the model

Fix GPU memory allocation issues

Author: lmxyy

nunchaku/models/transformers/transformer_flux.py

@@ -179,7 +179,8 @@ def forward_layer_at(
         encoder_hidden_states = encoder_hidden_states.to(original_dtype).to(original_device)
 
         return encoder_hidden_states, hidden_states
-
+    def __del__(self):
+        self.m.reset()
 
 ## copied from diffusers 0.30.3
 def rope(pos: torch.Tensor, dim: int, theta: int) -> torch.Tensor:

nunchaku/models/transformers/transformer_sana.py

@@ -130,7 +130,8 @@ def forward_layer_at(
             .to(original_dtype)
             .to(original_device)
         )
-
+    def __del__(self):
+        self.m.reset()
 
 class NunchakuSanaTransformer2DModel(SanaTransformer2DModel, NunchakuModelLoaderMixin):
     @classmethod