Bug 1443432 - Set scopes to push to Snap store's candidate channel r=mtabara

MozReview-Commit-ID: B2Z6bdDJw6f

--HG--
extra : rebase_source : 1a04ea56d68ae3f7a5408b9886f2d83952496d7b
extra : source : 517fe68440b3c9b31611a83e3208793e287dc56a

taskcluster/ci/release-snap/kind.yml

@@ -20,6 +20,7 @@ job-defaults:
    scopes:
       by-project:
          mozilla-beta: ["secrets:get:project/releng/snapcraft/firefox/edge"]
+         mozilla-release: ["secrets:get:project/releng/snapcraft/firefox/candidate"]
          default: []
    treeherder:
       platform: linux64/opt