deprecate built in wrappers for supersuit

gym/wrappers/frame_stack.py

@@ -1,6 +1,6 @@
 from collections import deque
 import numpy as np
-
+import warnings
 from gym.spaces import Box
 from gym import Wrapper
 
@@ -22,6 +22,7 @@ class LazyFrames(object):
     __slots__ = ("frame_shape", "dtype", "shape", "lz4_compress", "_frames")
 
     def __init__(self, frames, lz4_compress=False):
+        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_shape = tuple(frames[0].shape)
         self.shape = (len(frames),) + self.frame_shape
         self.dtype = frames[0].dtype