Fix deprecation warning: LICENSE is autodetected

[hugovk]

This can be omitted entirely because setuptools automatically includes LICENSE:

A list of glob patterns for license related files that should be included. If neither license_file nor license_files is specified, this option defaults to LICEN[CS]E*, COPYING*, NOTICE*, and AUTHORS*.

https://setuptools.pypa.io/en/latest/references/keywords.html#keywords

Before

$ python setup.py --licence
/Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/site-packages/setuptools/dist.py:775: UserWarning: Usage of dash-separated 'license-file' will not be supported in future versions. Please use the underscore name 'license_file' instead
  warnings.warn(
/Library/Frameworks/Python.framework/Versions/3.11/lib/python3.11/site-packages/setuptools/config/setupcfg.py:520: SetuptoolsDeprecationWarning: The license_file parameter is deprecated, use license_files instead.
  warnings.warn(msg, warning_class)
Apache Software License

After

$ python setup.py --licence
Apache Software License