Replace Conflicts python2-flask with Obsoletes and specify epoch
    
    Resolves https://bugzilla.redhat.com/show_bug.cgi?id=1767198
    
    The problem was:
    
    Error: Transaction check error:
      file /usr/bin/flask from install of python3-flask-1:1.0.2-8.fc32.noarch
      conflicts with file from package python2-flask-1:1.0.2-6.fc31.noarch
    
    That problem is caused by the missing epoch.
    However even when adding the epoch, there would be an error with an explicit conflict
    and python2-flask would need to be obsoleted via fedora-obsolete-packages.
    We save ourselves some coordination trouble and obsolete the package from python3-flask,
    despite arguably, some people might not like that as python3-flask
    does not, by some definitions, "replace" python2-flask.
    However, such definitions are hard to express.