remove send-announcements-to from closed series

We no longer use the send-announcements-to field for anything.

Change-Id: I605b86261e13e13f017264992090c5f726e3e605
Signed-off-by: Doug Hellmann <doug@doughellmann.com>

deliverables/juno/python-cliff.yaml

@@ -1,7 +1,6 @@
 ---
 launchpad: python-cliff
 team: OpenStackClient
-send-announcements-to: openstack-dev@lists.openstack.org
 releases:
   - version: 1.7.0
     projects: