Update post ref regex
This changed between gerrit 2.11 and 2.13.  It sends "refs/heads/"
on branches now.
trigger:
gerrit:
- event: ref-updated
- ref: ^(?!refs/).*$
+ ref: ^refs/heads/.*$
- pipeline:
name: pre-release
trigger:
gerrit:
- event: ref-updated
- ref: ^(?!refs/).*$
+ ref: ^refs/heads/.*$
failure:
smtp:
from: zuul@openstack.org
