• I have marked all applicable categories:
  • exception-raising fix
  • algorithm implementation fix
  • documentation modification
  • new feature
• If applicable, I have mentioned the relevant/related issue(s) Can collector/venv be aware of the environment state? #322

Less important but also useful:

• I have visited the source website
• I have searched through the issue tracker for duplicates
• I have mentioned version numbers, operating system and environment, where applicable:

  import tianshou, torch, sys
  print(tianshou.__version__, torch.__version__, sys.version, sys.platform)

This PR adds two tests/examples for using tianshou in applications with envs that consumes finite datasets.