Remove previous action from policy

ml-agents/mlagents/trainers/common/nn_policy.py

             self.prev_action = tf.placeholder(
                 shape=[None, len(self.act_size)], dtype=tf.int32, name="prev_action"
             )
-            prev_action_oh = tf.concat(
-                [
-                    tf.one_hot(self.prev_action[:, i], self.act_size[i])
-                    for i in range(len(self.act_size))
-                ],
-                axis=1,
-            )
-            hidden_policy = tf.concat([encoded, prev_action_oh], axis=1)
-
-                hidden_policy,
-                self.memory_in,
-                self.sequence_length_ph,
-                name="lstm_policy",
+                encoded, self.memory_in, self.sequence_length_ph, name="lstm_policy"
             )
 
             self.memory_out = tf.identity(memory_policy_out, "recurrent_out")