Add zuul jobs for gating

Turns out that without jobs defined patches don't really do much of
anything when submitted. Add some jobs.

Also, since this is a new utility that is not in use yet, and the first
use of it is on a bionic node anyway, just support python3.6.

Change-Id: I46ab534768a35329a6b9325c43ebc048ebfb368c

.zuul.yaml

@@ -0,0 +1,21 @@
+- project:
+    check:
+      jobs:
+        - tox-pep8
+        - tox-py27
+        - tox-py35
+        - tox-py36:
+            nodeset: ubuntu-bionic
+        - build-sphinx-docs:
+            vars:
+              sphinx_python: python3
+    gate:
+      jobs:
+        - tox-pep8
+        - tox-py27
+        - tox-py35
+        - tox-py36:
+            nodeset: ubuntu-bionic
+        - build-sphinx-docs:
+            vars:
+              sphinx_python: python3

pbrx/cmd/main.py

@@ -24,9 +24,10 @@ try:
 except ImportError:
     yaml = None
 
+import pbr.version
+
 from pbrx import containers
 from pbrx import siblings
-import pbr.version
 
 log = logging.getLogger("pbrx")
 

tox.ini

@@ -9,7 +9,6 @@ usedevelop = True
 install_command = pip install -c{env:UPPER_CONSTRAINTS_FILE:https://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt} {opts} {packages}
 setenv =
    VIRTUAL_ENV={envdir}
-   PYTHONWARNINGS=default::DeprecationWarning
    OS_STDOUT_CAPTURE=1
    OS_STDERR_CAPTURE=1
    OS_TEST_TIMEOUT=60