incompatible registration argument `tags` for latest version of gym

[IcarusWizard]

Hi, there. I find a compatibility issue.

According to https://github.com/openai/gym/commit/a99e8d153e94f532e5728b01b02b42e076334bf7, the latest version of gym has remove the argument tags in the registration function, which makes it incompatible with the registration process in this repo.

I suggest to add gym<0.16 to setup.py to tackle this issue. I have tested it on gym==0.15.7, and everything works fine.

[LecJackS]

pip install gym==0.15.7

solved the issue for me too.

For the record, console log:

TypeError: __init__() got an unexpected keyword argument 'tags'