Remove seeded_test fixture and migrate tests to numpy Generator API

[Utkarshkarki]

Migrate from seeded_test fixture to modern numpy Generator API

Replaces the legacy seeded_test fixture using np.random.seed() with a modern rng fixture using np.random.default_rng(). This eliminates global state pollution and enables thread-safe random number generation.

Changes:

• Replaced seeded_test with rng fixture in conftest.py
• Migrated 30+ tests across 6 files
• Updated all np.random.xxx() calls to rng.xxx() using Generator API

Benefits:

• No global state pollution
• Thread-safe parallel testing
• Modern numpy best practices
• Maintains reproducibility (same seed)

Closes #8035

[ricardoV94]

I rather move away from magic fixtures, just let each test create its own rng, it's not that much extra code

[Utkarshkarki]

Okay, I will make required changes

[Utkarshkarki]

Please check the changes

[ricardoV94]

Looks great!

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.47%. Comparing base (056e80c) to head (3a2131b).
⚠️ Report is 12 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #8037      +/-   ##
==========================================
+ Coverage   91.44%   91.47%   +0.02%     
==========================================
  Files         116      116              
  Lines       19002    19065      +63     
==========================================
+ Hits        17377    17440      +63     
  Misses       1625     1625              

see 12 files with indirect coverage changes

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[ricardoV94]

For last commit I prefer the more strict old test that no draws are close. Can you use a different seed and revert to the old check?

[Utkarshkarki]

I will look into it.

[Utkarshkarki]

Thanks for the suggestion!
I reverted to the original strict np.any(np.isclose(...)) checks and updated the random seeds.
I ran the affected AR, GARCH11, and Euler–Maruyama batched-size tests locally and they all pass.
I didn’t run the full test_timeseries.py file since it includes long MCMC tests that are very slow on Windows.

[ricardoV94]

need to run pre-commit

[Utkarshkarki]

yes i will do it

[Utkarshkarki]

I think all the changes are perfect now, and I have reviewed them. Please tell if any more changes are nedded.

[ricardoV94]

3 tests still have a changed condition that is less strict than before

[Utkarshkarki]

Please, can you review the changes once