style fix

Author: TS-Lee

art/attacks/extraction/copycat_cnn.py

@@ -163,4 +163,3 @@ def _check_params(self) -> None:
 
         if not isinstance(self.use_probability, bool):
             raise ValueError("The argument `use_probability` has to be of type bool.")
-

art/attacks/extraction/knockoff_nets.py

@@ -409,5 +409,3 @@ def _check_params(self) -> None:
             raise ValueError("The argument `verbose` has to be of type bool.")
         if not isinstance(self.use_probability, bool):
             raise ValueError("The argument `use_probability` has to be of type bool.")
-
-