Update to 3.0.0
    
    - convert to %pyproject macros
    - convert to %autorelease and %autochangelog
    - use %tox macro for test and doc generation
    - download sources from PyPI
    
    Related-to: https://review.rdoproject.org/r/q/Ie3e594a420c74cba485156dff7bccacf2eda73b2