fix Poetry dependency

[dancju]

• Upgraded Gym to Gymnasium Since SB3 will only support Gymnasium in the future. Some environment classes were upgraded because the API for reset() and step() was changed. We might want to update other environment classes as well.
• Upgraded Python to 3.10 in order to fix the dependency issue.
• Fixed minor bugs in Stock_NeurIPS2018_3_Backtest.ipynb and plot the backtesting results of all models (A2C, DDPG, PPO, TD3, SAC).

[zhumingpassional]

what is the meaning of alpaca-trade-api = "^3"?
what is the advantage of using gymnasium instead of gym?

[dancju]

• "^3" is equivalent to ">=3.0.0,<4.0.0"
  https://python-poetry.org/docs/dependency-specification/
• I committed poetry.lock because "always commit the lock file to your source repository" is a good practice.
  https://developerexperience.io/articles/lockfile
• Gym is no longer maintained by OpenAI. Other projects in the OpenAI universe will only support Gymnasium. Gymnasium also has a new vector API. With vector API, you can train a single-instrument-trading agent on multiple financial instruments simultaneously with multithreading. RL training would be much much faster.
  Roadmap Farama-Foundation/Gymnasium#12
• Even though SB3 has its own Vector API, SB3 will only support Gymnasium in the future. Currently, SB3 1.8.0 depends on Gym, and SB3 2.0.0a5 depends on Gymnasium.
  Add Gym 0.26 support DLR-RM/stable-baselines3#780

[zhumingpassional]

ok. thanks very much for your codes and response.

[dancju]

I forgot to mention, I changed three env files because the return type for reset() and step() is changed under the new API, and we might want to update all the env classes.

[zhumingpassional]

yes. I see

[HenryYYang]

I think this cause a regression fixed by #695