title: OpenAI gym 0.21.0 - AttributeError: module 'gym' has no attribute 'GoalEnv'
body: <p>I am trying to build a custom environment in openai gym format. I built my env and wanted to make sure that it is compatible with the gym format, so used the check_env() to do so. And the image shows the error that I faced. My gym version is 0.21.0. I think i shouldnt be facing this issue according the solutions that I've searched so far. It would be great if someone can help me with this. Thanks in advance and please let me know if my code is needed. <a href="https://i.stack.imgur.com/IvWub.png" rel="nofollow noreferrer">enter image description here</a></p>