Fix UserWarning: Defining your __torch_function__ as a plain method i…

…s deprecated and will be an error in future, please define it as a classmethod.

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 = {}