Remove python3.5 support

Also, use bionic node for ci.

Change-Id: Ia9cf9bf4726927a445ac3a5d9dfa86148d0691b5

.zuul.yaml

@@ -5,8 +5,6 @@
     post-run: playbooks/checkbuild/post.yaml
     vars:
       tox_envlist: checkbuild
-    nodeset: ubuntu-xenial
-
 - project:
     check:
       jobs:

{{cookiecutter.repo_name}}/setup.cfg

@@ -16,7 +16,7 @@ classifier =
     Programming Language :: Python :: 2
     Programming Language :: Python :: 2.7
     Programming Language :: Python :: 3
-    Programming Language :: Python :: 3.5
+    Programming Language :: Python :: 3.6
 
 [files]
 packages =

{{cookiecutter.repo_name}}/tox.ini

@@ -1,5 +1,5 @@
 [tox]
-envlist = pep8,py27-local,py35-local,py3-dj111-local,eslint,karma-local,docs-local,releasenotes
+envlist = pep8,py27-local,py36-local,py3-dj111-local,eslint,karma-local,docs-local,releasenotes
 minversion = 2.3.2
 skipsdist = True
 
@@ -54,12 +54,6 @@ commands =
   {[testenv:hz-local]commands}
   {[testenv]commands}
 
-[testenv:py35-local]
-basepython = python3.5
-commands =
-  {[testenv:hz-local]commands}
-  {[testenv]commands}
-
 [testenv:py36-local]
 basepython = python3.6
 commands =