deprecate built in wrappers for supersuit

gym/wrappers/atari_preprocessing.py

@@ -1,5 +1,5 @@
 import numpy as np
-
+import warnings
 import gym
 from gym.spaces import Box
 from gym.wrappers import TimeLimit
@@ -67,6 +67,7 @@ class AtariPreprocessing(gym.Wrapper):
             )
         self.noop_max = noop_max
         assert env.unwrapped.get_action_meanings()[0] == "NOOP"
+        warnings.warn("Gym\'s internal preprocessing wrappers are now deprecated. While they will continue to work for the foreseeable future, we strongly recommend using SuperSuit instead: https://github.com/PettingZoo-Team/SuperSuit")
 
         self.frame_skip = frame_skip
         self.screen_size = screen_size