[MNT] Remove __version__.py, define __version__ in __init__.py

[moksha-hub]

Summary

Removes the separate openml/__version__.py module and defines __version__ directly in openml/__init__.py as suggested in #1642.

Motivation

Having a dedicated __version__.py is an older pattern. Modern Python packages define the version string directly in __init__.py, which is simpler and avoids an unnecessary import level.

Changes

• openml/__init__.py: Replaced from .__version__ import __version__ with the version string defined inline:

  __version__ = "0.16.0"  # defined here directly, see issue #1642

• openml/__version__.py: File deleted (git rm).

All existing code that does import openml; openml.__version__ or from openml import __version__ continues to work unchanged, since __version__ is still exported from the top-level package.

Testing

No behavioural change — existing tests that access openml.__version__ will continue to pass.

Closes #1642

[moksha-hub]

@geetu040 please have a review.
Thank you.

[moksha-hub]

@geetu040 please have a review if any changes are required i can work on them or move onto the next issue.