Fix recent pyproject.toml build warnings

[bpkroth]

/tmp/build-env-vfr96wjs/lib/python3.13/site-packages/setuptools/config/pyprojecttoml.py:72: _ExperimentalConfiguration: `[tool.distutils]` in `pyproject.toml` is still *experimental* and likely to change in future releases.
  config = read_configuration(filepath, True, ignore_option_errors, dist)
/tmp/build-env-vfr96wjs/lib/python3.13/site-packages/setuptools/config/_apply_pyprojecttoml.py:82: SetuptoolsDeprecationWarning: `project.license` as a TOML table is deprecated
!!
        ********************************************************************************
        Please use a simple string containing a SPDX expression for `project.license`. You can also use `project.license-files`.
        By 2026-Feb-18, you need to update your project and remove deprecated calls
        or your builds will no longer be supported.
        See https://packaging.python.org/en/latest/guides/writing-pyproject-toml/#license for details.
        ********************************************************************************
!!
  corresp(dist, value, root_dir)
/tmp/build-env-vfr96wjs/lib/python3.13/site-packages/setuptools/config/_apply_pyprojecttoml.py:61: SetuptoolsDeprecationWarning: License classifiers are deprecated.
!!
        ********************************************************************************
        Please consider removing the following classifiers in favor of a SPDX license expression:
        License :: OSI Approved :: MIT License
        See https://packaging.python.org/en/latest/guides/writing-pyproject-toml/#license for details.
        ********************************************************************************
!!
  dist._finalize_license_expression()
/tmp/build-env-vfr96wjs/lib/python3.13/site-packages/setuptools/dist.py:760: SetuptoolsDeprecationWarning: License classifiers are deprecated.
!!
        ********************************************************************************
        Please consider removing the following classifiers in favor of a SPDX license expression:
        License :: OSI Approved :: MIT License
        See https://packaging.python.org/en/latest/guides/writing-pyproject-toml/#license for details.
        ********************************************************************************
!!