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: If9c46ca5a80128bb8c6a9bd9863c4c3305bae54c

.zuul.yaml

@@ -4,7 +4,6 @@
       - openstack-cover-jobs
       - openstack-lower-constraints-jobs
       - openstack-python-jobs
-      - openstack-python35-jobs
       - openstack-python36-jobs
     check:
       jobs:

setup.cfg

@@ -13,7 +13,7 @@ classifier =
     Operating System :: POSIX :: Linux
     Programming Language :: Python
     Programming Language :: Python :: 2.7
-    Programming Language :: Python :: 3.5
+    Programming Language :: Python :: 3.6
 
 [global]
 setup-hooks =

tox.ini

@@ -1,5 +1,5 @@
 [tox]
-envlist = py{27,35},pep8,cover
+envlist = py{27,36},pep8,cover
 minversion = 2.5
 skipsdist = True
 
@@ -30,15 +30,6 @@ commands =
   {[testenv]commands}
   stestr run {posargs}
 
-[testenv:py35]
-basepython = python3.5
-setenv =
-  {[testenv]setenv}
-  BLACKLIST_FILE={toxinidir}/test-blacklist-py3.txt
-commands =
-  {[testenv]commands}
-  stestr run --blacklist-file {env:BLACKLIST_FILE} {posargs}
-
 [testenv:py36]
 basepython = python3.6
 setenv =
@@ -103,9 +94,9 @@ ignore = H101,H301,H404,H405
 
 [testenv:lower-constraints]
 basepython = python3
-setenv = {[testenv:py35]setenv}
+setenv = {[testenv:py36]setenv}
 deps =
   -c{toxinidir}/lower-constraints.txt
   -r{toxinidir}/test-requirements.txt
   -r{toxinidir}/requirements.txt
-commands = {[testenv:py35]commands}
+commands = {[testenv:py36]commands}