Try running
yum clean all
and then try it again.
However, you need to careful since none of your repositories appear to be bona fida CentOS repositories (just by looking at the name.)
A slightly different version of python may create havoc when trying to upgrade other packages with python dependencies.
I don't have the trailing "_3.6" on mine which makes me suspicious that it might *not* be the correct version - but I might be wrong about that.
Also, all my packages end with ".i386" instead of "_3.6".
that's interesting, because my Centos-Base.repo looks like the attached file.