Dropping the py35 testing

All the integration testing has been moved to
Bionic now[1] and py3.5 is not tested runtime for
Train or stable/stein[2].

As per below ML thread, we are good to drop the py35
testing now:
http://lists.openstack.org/pipermail/openstack-discuss/2019-April/005097.html

[1] http://lists.openstack.org/pipermail/openstack-discuss/2019-April/004647.html
[2]
https://governance.openstack.org/tc/reference/runtimes/stein.html
https://governance.openstack.org/tc/reference/runtimes/train.html

Change-Id: I853f7de090387303ce0456e64b47c17d0bb9769b

.zuul.yaml

@@ -2,7 +2,6 @@
     templates:
       - openstack-lower-constraints-jobs
       - openstack-python-jobs
-      - openstack-python35-jobs
       - openstack-python36-jobs
       - openstack-python37-jobs
       - periodic-stable-jobs

setup.cfg

@@ -8,7 +8,7 @@ classifiers =
     Programming Language :: Python :: 2
     Programming Language :: Python :: 2.7
     Programming Language :: Python :: 3
-    Programming Language :: Python :: 3.5
+    Programming Language :: Python :: 3.6
     Environment :: OpenStack
     Intended Audience :: Information Technology
     Intended Audience :: System Administrators

tox.ini

@@ -1,5 +1,5 @@
 [tox]
-envlist = py36,py35,py27,pep8,genpolicy
+envlist = py36,py27,pep8,genpolicy
 minversion = 1.6
 skipsdist = True
 
@@ -26,8 +26,8 @@ commands = {toxinidir}/tools/cover.sh {posargs}
 basepython = python2.7
 commands = oslo_debug_helper -t sahara/tests/unit {posargs}
 
-[testenv:debug-py35]
+[testenv:debug-py36]
-basepython = python3.5
+basepython = python3.6
 commands = oslo_debug_helper -t sahara/tests/unit {posargs}
 
 [testenv:pep8]