Drop python 2.7 support and testing

OpenStack is dropping the py2.7 support in ussuri cycle.

oswin-tempest-plugin is ready with python 3 and ok to drop the
python 2.7 support.

Complete discussion & schedule can be found in
- http://lists.openstack.org/pipermail/openstack-discuss/2019-October/010142.html
- https://etherpad.openstack.org/p/drop-python2-support

Ussuri Communtiy-wide goal - https://review.opendev.org/#/c/691178/

Change-Id: I1e570f003a55fcbb3d4a628f788d5b34b76671db

.zuul.yaml

@@ -1,8 +1,7 @@
 - project:
     templates:
-      - openstack-python-jobs
       - openstack-python35-jobs
-      - openstack-python3-train-jobs
+      - openstack-python3-ussuri-jobs
       - check-requirements
     gate:
       queue: os-win

releasenotes/notes/drop-py-2-7-9c98090411bcd207.yaml

@@ -0,0 +1,6 @@
+---
+upgrade:
+  - |
+    Python 2.7 support has been dropped. Last release of oswin-tempest-plugin
+    to support py2.7 is OpenStack Train. The minimum version of Python now
+    supported by oswin-tempest-plugin is Python 3.5.

setup.cfg

@@ -14,8 +14,6 @@ classifier =
     Operating System :: POSIX :: Linux
     Operating System :: Microsoft :: Windows
     Programming Language :: Python
-    Programming Language :: Python :: 2
-    Programming Language :: Python :: 2.7
     Programming Language :: Python :: 3
     Programming Language :: Python :: 3.5
     Programming Language :: Python :: 3.6

tox.ini

@@ -1,9 +1,11 @@
 [tox]
-minversion = 2.0
+minversion = 3.1.1
-envlist = py27,py37,pypy,pep8
+envlist = py37,pypy,pep8
 skipsdist = True
+ignore_basepython_conflict = True
 
 [testenv]
+basepython = python3
 usedevelop = True
 install_command = pip install -c{env:UPPER_CONSTRAINTS_FILE:https://opendev.org/openstack/requirements/raw/branch/master/upper-constraints.txt} {opts} {packages}
 setenv =
@@ -17,23 +19,18 @@ deps = -r{toxinidir}/requirements.txt
 commands = python setup.py test --slowest --testr-args='{posargs}'
 
 [testenv:pep8]
-basepython = python3
 commands = flake8 {posargs}
 
 [testenv:venv]
-basepython = python3
 commands = {posargs}
 
 [testenv:cover]
-basepython = python3
 commands = python setup.py test --coverage --testr-args='{posargs}'
 
 [testenv:docs]
-basepython = python3
 commands = python setup.py build_sphinx
 
 [testenv:debug]
-basepython = python3
 commands = oslo_debug_helper {posargs}
 
 [flake8]