Fix dtype for actions

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

         if self.policy.use_continuous_act:
             actions = ModelUtils.list_to_tensor(batch["actions"]).unsqueeze(-1)
         else:
-            actions = ModelUtils.list_to_tensor(batch["actions"], dtype=torch.bool)
+            actions = ModelUtils.list_to_tensor(batch["actions"], dtype=torch.long)
 
         memories = [
             ModelUtils.list_to_tensor(batch["memory"][i])