Disable python3 tests failing due to Routes < 2.0
Disable python3 tests failing due to Routes < 2.0

At now, global-requirements has an entry:
Routes!=2.0,!=2.1,>=1.12.3
and this leads to Routes < 2.0 which is not compatible
with Python 3. This blocks updating of global requirements [1].
To avoid the situation, this commit disables python 3 related
error due to Routes version.

Closes-Bug: #1474266
Related to blueprint neutron-python3

[1] https://review.openstack.org/#/c/182746/

Change-Id: If5e6355505361cbefe04487b6d47ab9cc6ba861c
mahak/neutron,swdream/neutron,asgard-lab/neutron,openstack/neutron,vivekanand1101/neutron,mmnelemane/neutron,sebrandon1/neutron,apporc/neutron,mmnelemane/neutron,sebrandon1/neutron,adelina-t/neutron,mahak/neutron,swdream/neutron,glove747/liberty-neutron,paninetworks/neutron,shahbazn/neutron,takeshineshiro/neutron,JianyuWang/neutron,SamYaple/neutron,javaos74/neutron,dhanunjaya/neutron,MaximNevrov/neutron,openstack/neutron,dims/neutron,eonpatapon/neutron,apporc/neutron,chitr/neutron,adelina-t/neutron,cisco-openstack/neutron,mattt416/neutron,silenci/neutron,takeshineshiro/neutron,barnsnake351/neutron,wenhuizhang/neutron,dims/neutron,noironetworks/neutron,wolverineav/neutron,JianyuWang/neutron,igor-toga/local-snat,asgard-lab/neutron,huntxu/neutron,suneeth51/neutron,eayunstack/neutron,suneeth51/neutron,bigswitch/neutron,watonyweng/neutron,glove747/liberty-neutron,skyddv/neutron,skyddv/neutron,SamYaple/neutron,mahak/neutron,dhanunjaya/neutron,cloudbase/neutron,neoareslinux/neutron,chitr/neutron,jacknjzhou/neutron,openstack/neutron,klmitch/neutron,jumpojoy/neutron,bigswitch/neutron,sasukeh/neutron,jacknjzhou/neutron,klmitch/neutron,eayunstack/neutron,watonyweng/neutron,cisco-openstack/neutron,barnsnake351/neutron,shahbazn/neutron,yanheven/neutron,wolverineav/neutron,eonpatapon/neutron,cloudbase/neutron,silenci/neutron,javaos74/neutron,neoareslinux/neutron,vivekanand1101/neutron,wenhuizhang/neutron,jumpojoy/neutron,huntxu/neutron,noironetworks/neutron,yanheven/neutron,MaximNevrov/neutron,paninetworks/neutron,igor-toga/local-snat,sasukeh/neutron,mattt416/neutron