bug 1485680 - make the relpro action a hook. r=dustin

make the relpro action a hook.

Differential Revision: https://phabricator.services.mozilla.com/D5581

--HG--
extra : moz-landing-system : lando

taskcluster/taskgraph/actions/release_promotion.py

@@ -79,8 +79,7 @@ def get_flavors(graph_config, param):
     title='Release Promotion',
     symbol='${input.release_promotion_flavor}',
     description="Promote a release.",
-    # Bug 1485680
-    kind='task',
+    generic=False,
     order=500,
     context=[],
     available=is_release_promotion_available,