Ability to specify random seed in gym wrapper

[jurgisp]

The ability to set random seed was recently implemented in dm_env. It needs to be added to gym wrapper too.

[Howuhh]

@jurgisp also, I think with the release of https://github.com/Farama-Foundation/Shimmy (specific wrapper for dm_env here) you can deprecate or remove gym wrappers (well, they are already for the outdated gym interface). Shimmy should also handle (in theory, not tested yet) the seeding properly.

[Howuhh]

@jurgisp can I make a PR with gym updated to gymnasium and GymWrapper swapped to the wrapper from shimmy?

[jurgisp]

Please, go ahead! It would be nice to support that, but also keep the existing gym environments.