Trivial: Fix the pep8 warning

The yaml should start with "---"

Change-Id: Ibf8a41b10c0aa222c5ce1c78f39a33f70c2ffcb7

examples/playbook.yml

@@ -1,3 +1,4 @@
+---
 - name: Set up repo builds
   hosts: repo_all
   user: root

tests/ansible-role-requirements.yml

@@ -1,3 +1,4 @@
+---
 - name: apt_package_pinning
   src: https://git.openstack.org/openstack/openstack-ansible-apt_package_pinning
   scm: git

tests/test-data.yml

@@ -1,3 +1,4 @@
+---
 # Test data output from the py_pkgs lookup
 # To produce a fresh version of this, execute:
 # /opt/ansible-runtime/bin/python /etc/ansible/roles/plugins/lookup/py_pkgs.py \

zuul.d/project.yaml

@@ -1,3 +1,4 @@
+---
 # Copyright 2017, Rackspace US, Inc.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");