Remove some comments

ml-agents/mlagents/trainers/ppo/policy.py

         )
         self.optimizer.zero_grad()
         loss.backward()
-        # for grad,weight in zip(grads, self.model.trainable_weights):
-        #     if "critic/" in weight.name:
-        #         print(grad,weight.name)
+
-        # for stat_name, update_name in stats_needed.items():
-        #     update_stats[stat_name] = update_vals[update_name]
+
         return update_stats
 
     def get_value_estimates(