[Train] bump neutron-tempest-plugin to 0.8.0
[Train] bump neutron-tempest-plugin to 0.8.0

It fixes following bug:
https://bugs.launchpad.net/tripleo/+bug/1861102
and tested here: https://review.rdoproject.org/r/#/c/24683/

Change-Id: Ief1b14bdbfcc03cd5e299c2d17635ec05709103d
Signed-off-by: Chandan Kumar (raukadah) <37614c4f126be5146599b9d19fe2ba37ae0ea495@redhat.com>

redhat-openstack/rdoinfo