Zuul: add file extension to playbook path

Zuul now supports including the file extension on the playbook path
and omitting the extension is now deprecrated.  Update references
to include the extension.

Change-Id: I855444b69e037b1f6a01dac65e700a2a26e8be2b
diff --git a/.zuul.yaml b/.zuul.yaml
index ede4391..fccd3f3 100644
--- a/.zuul.yaml
+++ b/.zuul.yaml
@@ -17,22 +17,22 @@
     name: zuul-stream-functional
     parent: multinode
     nodeset: zuul-functional
-    pre-run: playbooks/zuul-stream/pre
-    run: playbooks/zuul-stream/functional
+    pre-run: playbooks/zuul-stream/pre.yaml
+    run: playbooks/zuul-stream/functional.yaml
     post-run:
-      - playbooks/zuul-stream/post
-      - playbooks/zuul-stream/post-ara
+      - playbooks/zuul-stream/post.yaml
+      - playbooks/zuul-stream/post-ara.yaml
     required-projects:
       - openstack/ara
     files:
-      - "zuul/ansible/callback/.*"
-      - "playbooks/zuul-stream/.*"
+      - zuul/ansible/callback/.*
+      - playbooks/zuul-stream/.*
 
 - job:
     name: zuul-migrate
     parent: unittests
-    run: playbooks/zuul-migrate/run
-    post-run: playbooks/zuul-migrate/post
+    run: playbooks/zuul-migrate/run.yaml
+    post-run: playbooks/zuul-migrate/post.yaml
     # We're adding zuul to the required-projects so that we can also trigger
     # this from project-config changes
     required-projects: