Remove spurious variable assignment

Remove a spurious variable assignment made with the return of
a tuple where the second value is not actually consumed.

fence/resources/openid/cilogon_oauth2.py

@@ -28,7 +28,7 @@ def get_auth_url(self):
             "authorization_endpoint", "https://cilogon.org/authorize"
         )
 
-        uri, state = self.session.create_authorization_url(
+        uri, _ = self.session.create_authorization_url(
             authorization_endpoint, prompt="login"
         )