Stop testing with py2

Python 2 is no longer supported. Python 3 is required.
This patch stop testing with python2 and issue the release note.

Change-Id: Idb4c37948b9ad5b19229a86fbbc42c2b63f585eb

.zuul.yaml

@@ -3,7 +3,6 @@
       - check-requirements
       - horizon-non-primary-django-jobs
       - openstack-lower-constraints-jobs-horizon
-      - openstack-python-jobs-horizon
       - openstack-python3-ussuri-jobs-horizon
       - publish-openstack-docs-pti
       - release-notes-jobs-python3

doc/requirements.txt

@@ -3,7 +3,6 @@
 # process, which may cause wedges in the gate later.
 
 openstackdocstheme>=1.18.1 # Apache-2.0
-sphinx!=1.6.6,!=1.6.7,>=1.6.2,<2.0.0;python_version=='2.7'  # BSD
 sphinx!=1.6.6,!=1.6.7,>=1.6.2;python_version>='3.4'  # BSD
 reno>=2.5.0 # Apache-2.0
 sphinxcontrib-httpdomain>=1.3.0 # BSD

releasenotes/notes/drop-python2-8f624e1c157ac04a.yaml

@@ -0,0 +1,4 @@
+---
+upgrade:
+  - |
+    Python 2 is no longer supported. Python 3 is required.

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

@@ -1,9 +1,11 @@
 [tox]
-envlist = py27,py36,py37,py3-{dj111,dj22},pep8
-minversion = 2.0
+envlist = py36,py37,py3-{dj111,dj22},pep8
+minversion = 3.1.1
 skipsdist = True
+ignore_basepython_conflict = True
 
 [testenv]
+basepython = python3
 usedevelop = True
 setenv = VIRTUAL_ENV={envdir}
          NOSE_WITH_OPENSTACK=1
@@ -21,15 +23,12 @@ commands =
   python manage.py test {posargs} --settings=blazar_dashboard.test.settings
 
 [testenv:pep8]
-basepython = python3
 commands = flake8 {posargs}
 
 [testenv:venv]
-basepython = python3
 commands = {posargs}
 
 [testenv:cover]
-basepython = python3
 commands =
   coverage erase
   coverage run {toxinidir}/manage.py test blazar_dashboard --settings=blazar_dashboard.test.settings {posargs} --exclude-dir=blazar_dashboard/test/integration_tests {posargs}
@@ -37,7 +36,6 @@ commands =
   coverage html --omit '.tox/cover/*' -d 'cover/htmlcov'
 
 [testenv:eslint]
-basepython = python3
 whitelist_externals = npm
 commands =
   npm install
@@ -45,14 +43,12 @@ commands =
   npm run lint
 
 [testenv:docs]
-basepython = python3
 deps =
      -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
      -r{toxinidir}/doc/requirements.txt
 commands = python setup.py build_sphinx
 
 [testenv:pdf-docs]
-basepython = python3
 deps = -r{toxinidir}/doc/requirements.txt
 whitelist_externals =
   make
@@ -61,7 +57,6 @@ commands =
   make -C doc/build/pdf
 
 [testenv:releasenotes]
-basepython = python3
 deps =
      -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
      -r{toxinidir}/doc/requirements.txt
@@ -75,7 +70,6 @@ exclude = .venv,.git,.tox,dist,*lib/python*,*egg,build,node_modules
 max-complexity = 20
 
 [testenv:lower-constraints]
-basepython = python3
 deps =
   -c{toxinidir}/lower-constraints.txt
   -r{toxinidir}/test-requirements.txt