fix: migrate from gym to gymnasium for NumPy 2.0+ compatibility

[ishanrajsingh]

• Replace gym dependency with gymnasium (maintained drop-in replacement)
• Update all gym imports to use gymnasium
• Add proper error handling for missing gymnasium dependency
• Add lazy loading of gymnasium in backtest module
• Fix hard crashes when using NumPy 2.0+

Fixes #2018

Description

Motivation and Context

How Has This Been Tested?

• [x] Pass the test by running: pytest qlib/tests/test_all_pipeline.py under upper directory of qlib.
• [x] If you are adding a new feature, test on your own test scripts.

Screenshots of Test Results (if appropriate):

1. Pipeline test:
2. Your own tests:

Types of changes

• [x] Fix bugs
• [ ] Add new feature
• [ ] Update documentation

[ishanrajsingh]

@microsoft-github-policy-service agree