[Small][Bugfix] Fix Environment make_dataset method (from main README)

[pruksmhc]

Description

Following the evaluation example in the README was throwing errors in the make_dataset step.

This PR fixes that.

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Test improvement

Testing

• All existing tests pass when running uv run pytest locally.
  All tests passed except for a few environment loads (due to lack of API keys).
• New tests have been added to cover the changes

Checklist

• My code follows the style guidelines of this project as outlined in AGENTS.md
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• Any dependent changes have been merged and published

Additional Notes

---

Note

Fixes dataset creation errors in evaluation by adjusting method binding.

• Convert Environment.make_dataset to a staticmethod, preventing unintended self binding and aligning with README usage

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