Stop testing python2.7

Python 2.7 support has been dropped. Last release of Cyborg to support
py2.7 is OpenStack Train. The minimum version of Python now
supported by Cyborg is Python 3.6.

Depends-On: https://review.opendev.org/#/c/691766/
Change-Id: Ie87ef7727b50d8d5ca43f0283c5688199c35412e

.zuul.yaml

@@ -1,6 +1,5 @@
 - project:
     templates:
-      - openstack-python-jobs
       - openstack-cover-jobs
       - check-requirements
       - release-notes-jobs-python3

releasenotes/notes/drop-python2-support-in-ussuri-e64f79db4e88ca19.yaml

@@ -0,0 +1,5 @@
+---
+other:
+  - |
+    Drop support for python2 as per `this
+    <https://governance.openstack.org/tc/resolutions/20180529-python2-deprecation-timeline.html#python2-deprecation-timeline>`_ message

setup.cfg

@@ -13,8 +13,6 @@ classifier =
     License :: OSI Approved :: Apache Software License
     Operating System :: POSIX :: Linux
     Programming Language :: Python
-    Programming Language :: Python :: 2
-    Programming Language :: Python :: 2.7
     Programming Language :: Python :: 3
     Programming Language :: Python :: 3.6
     Programming Language :: Python :: 3.7

tox.ini

@@ -1,12 +1,13 @@
 [tox]
 minversion = 2.0
-envlist = py27,py36,py37,pep8
+envlist = py36,py37,pep8
 skipsdist = True
 
 [testenv]
 usedevelop = True
 whitelist_externals = rm
 install_command = {[testenv:common-constraints]install_command}
+basepython = python3
 setenv =
     VIRTUAL_ENV={envdir}
     OS_TEST_PATH=cyborg/tests/unit
@@ -18,18 +19,15 @@ commands = rm -f .testrepository/times.dbm
            stestr run --slowest {posargs}
 
 [testenv:common-constraints]
-basepython = python3
 install_command = pip install -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master} {opts} {packages}
 
 [testenv:genpolicy]
-basepython = python3
 sitepackages = False
 envdir = {toxworkdir}/venv
 commands =
     oslopolicy-sample-generator --config-file=tools/config/cyborg-policy-generator.conf
 
 [testenv:genconfig]
-basepython = python3
 sitepackages = False
 envdir = {toxworkdir}/venv
 commands =
@@ -42,29 +40,24 @@ commands =
 # separately, outside of the requirements files, and develop mode disabled
 # explicitly to avoid unnecessarily installing the checked-out repo too (this
 # further relies on "tox.skipsdist = True" above).
-basepython = python3
 deps = bindep
 commands = bindep test
 usedevelop = False
 
 
 [testenv:pep8]
-basepython = python3
 commands =
     flake8
     doc8 doc/source/ CONTRIBUTING.rst HACKING.rst README.rst
 
 [testenv:pep8-constraints]
-basepython = python3
 install_command = {[testenv:common-constraints]install_command}
 commands = flake8 {posargs}
 
 [testenv:venv]
-basepython = python3
 commands = {posargs}
 
 [testenv:cover]
-basepython = python3
 setenv =
     PYTHON=coverage run --source cyborg --parallel-mode
 commands =
@@ -79,18 +72,15 @@ ignore-path = .venv,.git,.tox,*cyborg/locale*,*lib/python*,*cyborg.egg*,api-ref/
 
 
 [testenv:docs]
-basepython = python3
 deps = -r{toxinidir}/doc/requirements.txt
 commands =
     sphinx-build -W -b html doc/source doc/build/html
 
 [testenv:releasenotes]
-basepython = python3
 deps = -r{toxinidir}/doc/requirements.txt
 commands = sphinx-build -a -W -E -d releasenotes/build/doctrees -b html releasenotes/source releasenotes/build/html
 
 [testenv:debug]
-basepython = python3
 commands = oslo_debug_helper -t cyborg/tests {posargs}
 
 [testenv:api-ref]