Define publish-to-pypi-stable-only template

Deprecated deliverables only do the release on
stable branches only not on master. But existing
publish-to-pypi template does not have the branch
matcher to exclude the master gate from running the
release jobs.

This commit defines a new template for such deprecated
repo publish-to-pypi-stable-only which exclude the master
branch to run the release jobs.

This new template will be used in all the deprected repo so
that if needed we can update the master conent which is README.rst
for example: https://review.opendev.org/c/openstack/neutron-fwaas/+/800140

Change-Id: Icc98e4f231413365af6a4f2270282565335e343c

zuul.d/project-templates.yaml

@@ -191,6 +191,49 @@
             dependencies:
               - release-openstack-python
 
+- project-template:
+    name: publish-to-pypi-stable-only
+    description: |
+      Publish a Python package to PyPI, then send release announcement
+      emails and propose updates to upper-constraints as needed. This
+      template is supposed to be used for deliverables having stable
+      branch release only, means deprecated deliverables who still
+      support stable release.
+    check:
+      jobs:
+        - test-release-openstack:
+            # NOTE(gmann): Do not run the release job on master branch.
+            # This template is supposed to be used for stable only release.
+            branches: ^(?!master).*$
+    gate:
+      jobs:
+        - test-release-openstack:
+            branches: ^(?!master).*$
+    pre-release:
+      jobs:
+        - release-openstack-python:
+            branches: ^(?!master).*$
+        - announce-release:
+            branches: ^(?!master).*$
+            dependencies:
+              - release-openstack-python
+        - propose-update-constraints:
+            branches: ^(?!master).*$
+            dependencies:
+              - release-openstack-python
+    release:
+      jobs:
+        - release-openstack-python:
+            branches: ^(?!master).*$
+        - announce-release:
+            branches: ^(?!master).*$
+            dependencies:
+              - release-openstack-python
+        - propose-update-constraints:
+            branches: ^(?!master).*$
+            dependencies:
+              - release-openstack-python
+
 - project-template:
     name: publish-xstatic-to-pypi
     description: |