setup: Use a list instead of a tuple for 'classifiers'
setup: Use a list instead of a tuple for 'classifiers'

Fixes a warning on Python 3.7:

  Warning: 'classifiers' should be a list, got type 'tuple'

Maybe it could prevent other issues too:
https://github.com/pypa/pypi-legacy/issues/670

ulfalizer/Kconfiglib,ulfalizer/Kconfiglib