Enable Legacy Warnings (#2617)

* Update pendulum.py

* version warnings

* black

* try except

* update notices version

* Exception

* nosec

* black

* no loop, stderr

* black

gym/__init__.py

@@ -15,6 +15,19 @@ from gym import vector
 from gym import wrappers
 import os
 
+
 __all__ = ["Env", "Space", "Wrapper", "make", "spec", "register"]
 
 os.environ["PYGAME_HIDE_SUPPORT_PROMPT"] = "hide"
+
+try:
+    import gym_notices.notices as notices
+    import sys
+
+    # print version warning if necessary
+    notice = notices.notices.get(__version__)
+    if notice is not None:
+        print(notice, file=sys.stderr)
+
+except Exception:  # nosec
+    pass

setup.py

@@ -49,6 +49,7 @@ setup(
         "numpy>=1.18.0",
         "cloudpickle>=1.2.0",
         "importlib_metadata>=4.10.0; python_version < '3.10'",
+        "gym_notices>=0.0.4",
     ],
     extras_require=extras,
     package_data={