Add rally-tox-py39 job

Python3.9 has been added by the TC to the list of supported python
versions, so it will be nice to test against it.

Signed-off-by: Dr. Jens Harbott <harbott@osism.tech>
Change-Id: I06c0c4bc4f23e8255c539ff54d258ae1c7eb717b

.zuul.d/python-jobs.yaml

@@ -89,6 +89,17 @@
     vars:
       tox_env: py38
 
+- job:
+    name: rally-tox-py39
+    parent: rally-tox-base
+    description: |
+      Run unit test for rally project.
+
+      Uses tox with the ``py39`` environment.
+    nodeset: ubuntu-focal
+    vars:
+      tox_env: py39
+
 - job:
     name: rally-tox-samples
     parent: rally-tox-base

.zuul.d/zuul.yaml

@@ -12,6 +12,7 @@
         - rally-tox-py36
         - rally-tox-py37
         - rally-tox-py38
+        - rally-tox-py39
         - rally-tox-samples
         - rally-tox-functional
         - rally-tox-functional-py38
@@ -29,6 +30,7 @@
         - rally-tox-py36
         - rally-tox-py37
         - rally-tox-py38
+        - rally-tox-py39
         - rally-tox-functional
         - rally-tox-self
         - rally-install-ubuntu-bionic

tox.ini

@@ -40,6 +40,9 @@ basepython = python3.7
 [testenv:py38]
 basepython = python3.8
 
+[testenv:py39]
+basepython = python3.9
+
 [testenv:samples]
 commands =
   find . -type f -name "*.pyc" -delete