tox.ini : update Ansible pin
ansible-lint is incompatible with Ansible 2.7 which is now causing
failures.  Update to current Zuul versions.
@@ -26,9 +26,11 @@ setenv =
# Add dependencies here since other jobs use python2 and zuul requires
# python3.
deps =
- # Pin ansible to common version we use, otherwise ansible-lint
- # would pull in latest version.
- ansible>=2.7.0,<2.8
+ # ansible-lint brings in the latest version of ansible, but we
+ # keep this in sync with what Zuul uses so we don't allow though
+ # things from a later ansible that would actually fail in
+ # production.
+ ansible>=2.8,<=2.9
ansible-lint>=4.2.0,<5
hacking>=2.0.0,<2.1.0
bashate>=0.2
