setup.cfg: remove deprecated classifier

[yegorich]

What do these changes do?

Remove the deprecated license classifier.

Fixes the following warning:

/usr/lib/python3.13/site-packages/setuptools/dist.py:759: SetuptoolsDeprecationWarning: License classifiers are deprecated. !!

        ********************************************************************************
        Please consider removing the following classifiers in favor of a SPDX license expression:

        License :: OSI Approved :: Apache Software License

        See https://packaging.python.org/en/latest/guides/writing-pyproject-toml/#license for details.
        ********************************************************************************

!!

Are there changes in behavior for the user?

No.

Related issue number

There are no known issues.

Checklist

• I think the code is well written
• Unit tests for the changes exist
• Documentation reflects the changes

[codspeed-hq]

CodSpeed Performance Report

Merging #1550 will not alter performance

_{Comparing yegorich:fix-licence (bf0ab16) with master (4b49680)}

Summary

✅ 101 untouched benchmarks

[webknjaz]

This needs a packaging change note.