e82379c47f
Running multiple training runs in parallel (with, for example, joblib) fails on macOS due to a change in the standard context for multiprocessing (see [here](https://stackoverflow.com/questions/65098398/why-using-fork-works-but-using-spawn-fails-in-python3-8-multiprocessing) or [here](https://www.reddit.com/r/learnpython/comments/g5372v/multiprocessing_with_fork_on_macos/)). This PR adds the ability to explicitly set a multiprocessing context for the SubProcEnvWorker (similar to gymnasium's [AsyncVecEnv](https://github.com/Farama-Foundation/Gymnasium/blob/main/gymnasium/vector/async_vector_env.py)). --------- Co-authored-by: Maximilian Huettenrauch <m.huettenrauch@appliedai.de> Co-authored-by: Michael Panchenko <35432522+MischaPanch@users.noreply.github.com>