We need to pin enum34 on python2 because upstream broke it.
Also, we should not install zuul in python2, because it's not targetted
at python2. It's only here so that linters can deal with zuul_return
and other things from its library, so it should be fine to not install
it for python2 unittests.
GitPython was in here as a pin to the versions that support python3
for zuul. Since we're constraining zuul to only python3, we don't need
to mention GitPython at all.
Update the siblings unit test to use requests as the package we expect
to be already installed since we're no longer installing zuul for
python2.
Fedora 29 got archived upstream:
http://mirror.sjc1.vexxhost.openstack.org/fedora/releases/29/README
So we need to switch to fedora 30.
Change-Id: I69e0b03f624ba45889916f89c0912df667aaf096
d36ba50765