Fix lower-constraints job
Fix lower-constraints job

lower-constraints job does not need linters, So we can drop
mccabe to fix the lower-constraints job.

Change-Id: I0342d9a3dfb441f89aa9d100b4eadbc6d49f87e5

openstack/sahara-dashboard,openstack/sahara-dashboard,openstack/sahara-dashboard,openstack/sahara-dashboard