Fix SAC scoping

ml-agents/mlagents/trainers/sac/network.py

                 self.h_size,
                 0,
                 vis_encode_type=vis_encode_type,
-                stream_scopes=["policy/", "critic/value/"],
+                stream_scopes=["critic/value/"],
             )
         hidden_critic = hidden_streams[0]
         return hidden_critic