bug: need to fix how the wheel is built

[sbillinge]

Problem

Recent release resulted in warnings from pypi about an incorrect RECORD that will be deprecated in the future:

This email is notifying you of an upcoming deprecation that we have determined may affect you as a result of your recent upload to 'diffpy.pdffit2'.

In the future, PyPI will require the file contents of all newly uploaded wheel distributions to match their included RECORD file. Specifically, your recent upload of 'diffpy_pdffit2-1.6.0-cp314-cp314-manylinux_2_39_x86_64.whl' has file contents that do not match the included RECORD file.

Any files already uploaded can remain in place as-is and do not need to be updated or removed.

In most cases, this can be resolved by upgrading the version of your build tooling to a later version that correctly records wheel contents. You do not need to remove the file.

Please read this [PyPI blog post](https://blog.pypi.org/posts/2025-08-07-wheel-archive-confusion-attacks) for more information. If you have questions, you can email [admin@pypi.org](mailto:admin@pypi.org) to communicate with the PyPI administrators.

Proposed solution

Fix this problem and make a new release. @zmx27 could you take a look at this if you get a chance?