`project.license` as a TOML table is deprecated

[delucchi-cmu]

See warnings:

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`. (Both options available on setuptools>=77.0.0).
   
           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.
           ********************************************************************************
   
   !!

[delucchi-cmu]

Also:

SetuptoolsDeprecationWarning: License classifiers are deprecated.

   !!
   
           ********************************************************************************
           Please consider removing the following classifiers in favor of a SPDX license expression:
   
           License :: OSI Approved :: BSD License
   
           See https://packaging.python.org/en/latest/guides/writing-pyproject-toml/#license for details.
           ********************************************************************************
   

[delucchi-cmu]

And if you use the newer format, you also need to update the check in .pre-commit-config.yaml

    # Verify that pyproject.toml is well formed
  - repo: https://github.com/abravalheri/validate-pyproject
    rev: v0.24.1