Update py35 jobs to py37, run on Xenial

The upstream OpenStack default node type changed yesterday
from Ubuntu Xenial to Bionic. We have a number of jobs pegged
directly to py35 which is no longer available in Bionic.

We can either pin the py35 jobs to Xenial nodes or update them
to py36 or py37.  OpenStack is supporting both of those for the
Stein release, since StarlingX does not have any position on
Python 3 versions (yet!) I am suggesting we move straight to py37
and in the case of issues now make these jobs non-voting until
any incompatibilities are resolved.

Remove the stable/queens upper-constraints from nfv/tox.ini

Change-Id: Ibb0260d29e48447d770f76211ad4af9b736d7907
Signed-off-by: Dean Troyer <dtroyer@gmail.com>

.zuul.yaml

@@ -9,7 +9,7 @@
         - openstack-tox-linters
         - nfv-tox-pep8
         - nfv-tox-py27
-        - nfv-tox-py35
+        - nfv-tox-py37
         - nfv-tox-pylint
         - nova-api-proxy-tox-pep8
         - nova-api-proxy-tox-pylint
@@ -22,7 +22,7 @@
         - openstack-tox-linters
         - nfv-tox-pep8
         - nfv-tox-py27
-        - nfv-tox-py35
+        - nfv-tox-py37
         - nfv-tox-pylint
         - nova-api-proxy-tox-pep8
         - nova-api-proxy-tox-pylint
@@ -43,14 +43,16 @@
       tox_extra_args: -c nfv/tox.ini
 
 - job:
-    name: nfv-tox-py35
+    name: nfv-tox-py37
     parent: tox
-    description: Run py35 for nfv
+    description: Run py37 for nfv
     required-projects:
       - openstack/stx-fault
     vars:
-      tox_envlist: py35
+      tox_envlist: py37
       tox_extra_args: -c nfv/tox.ini
+      bindep_profile: test py37
+      python_version: 3.7
 
 - job:
     name: nfv-tox-pep8

nfv/tox.ini

@@ -16,7 +16,7 @@ stxdir = {toxinidir}/../..
 
 [testenv]
 recreate = True
-install_command = pip install -c{env:UPPER_CONSTRAINTS_FILE:https://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt?h=stable/queens} {opts} {packages}
+install_command = pip install -c{env:UPPER_CONSTRAINTS_FILE:https://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt} {opts} {packages}
 whitelist_externals = cp
 
 [nfv]
@@ -81,7 +81,7 @@ enable-extensions = H106,H203
 max-line-length = 84
 
 [testenv:pep8]
-basepython = python3.5
+basepython = python3
 usedevelop = False
 skip_install = True
 deps = -r{toxinidir}/test-requirements.txt
@@ -133,8 +133,8 @@ commands = cp -v {[nfv]nfv_base_dir}/nfv-tests/nfv_unit_tests/test_data/nfv_vim_
            stestr --test-path={[nfv]nfv_base_dir}/nfv-tests/nfv_unit_tests/tests run '{posargs}'
            stestr slowest
 
-[testenv:py35]
-basepython = python3.5
+[testenv:py37]
+basepython = python3.7
 deps = {[nfv]deps}
        coverage
        fixtures