Use warnings.warn instead of logger.warning for deprecation notices

[ArnavBalyan]

Changes

• logger.warning does not fire in most CI/applications unless the app configures it.
• warnings.warn is visible by default to pytest and python -W
• Switch to warnings to so deprecation notices can reach users/CI tests.

How I tested this

• N/A

Notes

Checklist

• PR has an informative and human-readable title (this will be pulled into the release notes)
• Changes are limited to a single goal (no scope creep)
• Code passed the pre-commit check & code is left cleaner/nicer than when first encountered.
• Any change in functionality is tested
• New functions are documented (with a description, list of inputs, and expected output)
• Placeholder code is flagged / future TODOs are captured in comments
• Project documentation has been updated if adding/changing functionality.

[ArnavBalyan]

cc @skrawcz