Fix license warnings from build

[jeromekelleher]

Getting

tmp/build-env-th3xsgb3/lib/python3.10/site-packages/setuptools/config/_apply_pyprojecttoml.py:82: SetuptoolsDeprecationWarning: `project.license` as a TOML table is deprecated
5830
!!
5831
        ********************************************************************************
5832
        Please use a simple string containing a SPDX expression for `project.license`. You can also use `project.license-files`. (Both options available on setuptools>=77.0.0).
5833
        By 2027-Feb-18, you need to update your project and remove deprecated calls
5834
        or your builds will no longer be supported.
5835
        See https://packaging.python.org/en/latest/guides/writing-pyproject-toml/#license for details.
5836
        ********************************************************************************
5837
!!
5838
  corresp(dist, value, root_dir)
5839
/tmp/build-env-th3xsgb3/lib/python3.10/site-packages/setuptools/config/_apply_pyprojecttoml.py:61: SetuptoolsDeprecationWarning: License classifiers are deprecated.
5840
!!
5841
        ********************************************************************************
5842
        Please consider removing the following classifiers in favor of a SPDX license expression:
5843
        License :: OSI Approved :: GNU General Public License v3 or later (GPLv3+)
5844
        See https://packaging.python.org/en/latest/guides/writing-pyproject-toml/#license for details.
5845
        ********************************************************************************
5846
!!
5847
  dist._finalize_license_expression()
5848
/tmp/build-env-th3xsgb3/lib/python3.10/site-packages/setuptools/dist.py:765: SetuptoolsDeprecationWarning: License classifiers are deprecated.
5849
!!
5850
        ********************************************************************************
5851
        Please consider removing the following classifiers in favor of a SPDX license expression:
5852
        License :: OSI Approved :: GNU General Public License v3 or later (GPLv3+)
5853
        See https://packaging.python.org/en/latest/guides/writing-pyproject-toml/#license for details.
5854
        ********************************************************************************
5855
!!