Add openstack-python37-jobs-* templates

Create 4 new Python 3.7 project-templates for jobs to use. This
includes base, horizon, neutron, and non-voting variants.

Change-Id: I72619f1d98a17c390661559f598660ecf54a8bca

zuul.d/project-templates.yaml

@@ -602,6 +602,65 @@
         - openstack-tox-py36:
             voting: false
 
+- project-template:
+    name: openstack-python37-jobs
+    description: |
+      Runs unit tests for an OpenStack Python project under cPython
+      version 3.7.
+    check:
+      jobs:
+        - openstack-tox-py37
+    gate:
+      jobs:
+        - openstack-tox-py37
+
+- project-template:
+    name: openstack-python37-jobs-horizon
+    description: |
+      The standard openstack-python37-jobs but with horizon added as a
+      required-projects. The dashboard projects currently need this
+      due to how the tox_install.sh zuul-cloner's horizon for them.
+    check:
+      jobs:
+        - openstack-tox-py37:
+            required-projects:
+              - openstack/horizon
+    gate:
+      jobs:
+        - openstack-tox-py37:
+            required-projects:
+              - openstack/horizon
+
+- project-template:
+    name: openstack-python37-jobs-neutron
+    description: |
+      The standard :zuul:project_template:`openstack-python37-jobs`
+      but with neutron added as a required-projects. This checks out
+      the project code and allows tox_install_siblings to use neutron
+      when building the venv.
+    check:
+      jobs:
+        - openstack-tox-py37:
+            required-projects:
+              - openstack/neutron
+    gate:
+      jobs:
+        - openstack-tox-py37:
+            required-projects:
+              - openstack/neutron
+
+- project-template:
+    name: openstack-python37-jobs-nonvoting
+    description: |
+      Runs unit tests for an OpenStack Python project under cPython
+      version 3.7.
+
+      The job is non-voting.
+    check:
+      jobs:
+        - openstack-tox-py37:
+            voting: false
+
 - project-template:
     name: openstack-python-jobs-no-constraints
     description: |