Add zuul.yaml for zuulv3

This converts the tox-lint job to zuulv3. There is a standard
openstack-tox-linters that we can rely on.

Change-Id: I31eb188d9bde1fa0db5a46b3fa8b412f729d939e

.zuul.yaml

@@ -0,0 +1,10 @@
+- project:
+    name: openstack/rpm-packaging
+    templates:
+      - merge-check
+    check:
+      jobs:
+        - openstack-tox-linters
+    gate:
+      jobs:
+        - openstack-tox-linters

tox.ini

@@ -11,11 +11,15 @@ install_command = pip install -U -c{env:UPPER_CONSTRAINTS_FILE:https://git.opens
 deps = -r{toxinidir}/test-requirements.txt
 passenv = http_proxy HTTP_PROXY https_proxy HTTPS_PROXY no_proxy NO_PROXY
 
-[testenv:lint]
+[testenv:linters]
 commands =
   {toxinidir}/tools/run_renderspec.sh {toxinidir}
   {toxinidir}/tools/run_specchecks.sh {toxinidir}
   {toxinidir}/tools/run_speccleaner.sh {toxinidir}
 
+# compat. remove me
+[testenv:lint]
+commands = {[testenv:linters]commands}
+
 [testenv:venv]
 commands = {posargs}