limit *.py[co] %exclude to el7
    
    The exclusion was added in 9febbf3 (disable automatic compilation of
    *.py files outside of python sitelib, 2018-06-15).  Since that time, no
    supported Fedora releases need it and the only EL release which does is
    EL7.  Update the comment to reflect this and only use %exclude on EL7.