Fix issue "UserWarning: Positional args are being deprecated, use kwa…

…rgs instead. Refer to https://pytorch.org/docs/master/generated/torch.nn.Module.html#torch.nn.Module.state_dict for details."

src/brevitas/quant_tensor/__init__.py

@@ -79,6 +79,7 @@ def training(self):
         else:
             return None
 
+    @classmethod
     def __torch_function__(self, func, types, args=(), kwargs=None):
         if kwargs is None:
             kwargs = {}