Remove unneeded string format

Signed-off-by: Ivan Kanakarakis <ivan.kanak@gmail.com>

Author: c00kiemon5ter

src/saml2/cryptography/symmetric.py

@@ -89,7 +89,7 @@ def build_cipher(self, *args, **kwargs):
             "The 'Fernet' class does not need a build_cipher method."
             "Remove any calls to this method. "
             "In the next version, this method will be removed."
-        ).format(name=cls.__name__, type=type(cls).__name__)
+        )
         _warnings.warn(_deprecation_msg, DeprecationWarning)