Fix: set render_mode in tianshou tutorials (#853)

[RaffaeleGalliera]

Description

Set render_mode in tianshou tutorials when environment initialization is performed, which otherwise would cause the following error:

pettingzoo/classic/rps/rps.py", line 228, in render
   gymnasium.logger.WARN(
TypeError: 'int' object is not callable.

Fixes #853

Type of change

• Bug fix (non-breaking change which fixes an issue)

Checklist:

• I have run the pre-commit checks with pre-commit run --all-files (see CONTRIBUTING.md instructions to set it up)
• I have run pytest -v and no errors are present.
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I solved any possible warnings that pytest -v has generated that are related to my code to the best of my knowledge.
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

[WillDudley]

Thanks for this. This is a weird bug. It passes the CI, and on my machine tuts #2 and #3 run to completion. But, this is a known one, and was overlooked here. WARN has been changed to the correct warn but it isn't on PyPi yet - I'll release it soon.