Remove %__pythondist_provides from pythondist.attr.
    
    %__python_provides in RHEL's python3-rpm-generators does the same thing,
    so this wastes time by running it twice. Additionally, our version is
    out of date and packages built against alternative python stacks
    incorrectly have python3dist(X) Provides.
    
    Related: https://bugzilla.redhat.com/1776941
    Related: https://git.centos.org/rpms/python-rpm-generators/c/d809defd2ccab8945493103694fe96ffe6ea3a3c?branch=c8s