Fix SAC test

ml-agents/mlagents/trainers/tests/torch/test_sac.py

     update_buffer[RewardSignalUtil.rewards_key("extrinsic")] = update_buffer[
         BufferKey.ENVIRONMENT_REWARDS
     ]
+    # Mock out value memories
+    update_buffer[BufferKey.CRITIC_MEMORY] = update_buffer[BufferKey.MEMORY]
     return_stats = optimizer.update(
         update_buffer,
         num_sequences=update_buffer.num_experiences // optimizer.policy.sequence_length,