SetuptoolsDeprecationWarning: License classifiers are deprecated.

[ifduyue]

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.
    ********************************************************************************

!!