Change openstack-dev to openstack-discuss (#7)

Mailing lists have been updated. Openstack-discuss replaces openstack-dev.
diff --git a/setup.cfg b/setup.cfg
index 5ee9609..6836aa1 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -4,7 +4,7 @@
 description-file =
     README.rst
 author = OpenStack
-author-email = openstack-dev@lists.openstack.org
+author-email = openstack-discuss@lists.openstack.org
 home-page = https://docs.openstack.org/tungsten-tempest/latest/
 classifier =
     Environment :: OpenStack