fix tf bc test

ml-agents/mlagents/trainers/tf/components/bc/module.py

             self.policy.sequence_length_ph: self.policy.sequence_length,
         }
         feed_dict[self.model.action_in_expert] = mini_batch_demo["actions"]
-        if self.policy.behavior_spec.is_action_discrete():
+        if self.policy.action_spec.is_action_discrete():
-                    sum(self.policy.behavior_spec.discrete_action_branches),
+                    sum(self.policy.action_spec.discrete_action_branches),
                 ),
                 dtype=np.float32,
             )