⚗️ ✨ Update OpenAI gym to gymnasium

[Yonv1943]

Update OpenAI gym to gymnasium

In the github of gym, there are: The team that has been maintaining Gym since 2021 has moved all future development to Gymnasium, a drop in replacement for Gym (import gymnasium as gym), and Gym will not be receiving any future updates. Please switch over to Gymnasium as soon as you're able to do so. If you'd like to read more about the story behind this switch, please check out this blog post.

• OpenAI/gym
• Farama-Foundation/Gymnasium

ElegantRL plan to updategym to gymnasium.

[Yonv1943]

We plan to update the OpenAI gym to gymnasium (#274) and using YAML to save configuration files for training instead of using Python files (#275).