Only verify bundled provides --without bootstrap, supply all vendor files at once
    
    The initial build for new Python version does not yet have the script available.
    Multiple input files for the script are supported since Fedora 35,
    but we keep the versioned BuildRequires for RHEL's sake.
    
    The $PWD makes no sense --without bootstrap and the script should not even import pkg_resources,
    see https://src.fedoraproject.org/rpms/python-rpm-generators/pull-request/59