ci: Integrate with GNOME Release Service

.gitlab-ci.yml

@@ -1,6 +1,10 @@
 include:
   - project: 'gnome/citemplates'
     file: 'flatpak/flatpak_ci_initiative.yml'
+  - component: gitlab.gnome.org/GNOME/citemplates/release-service@master
+    inputs:
+      dist-job-name: "build-flatpak"
+      tarball-artifact-path: "${TARBALL_ARTIFACT_PATH}"
 
 variables:
   APP_ID: "org.gnome.Calendar.Devel"
@@ -9,6 +13,7 @@ variables:
   GIT_SUBMODULE_STRATEGY: 'normal'
   MANIFEST_PATH: "build-aux/org.gnome.Calendar.json"
   RUNTIME_REPO: "https://nightly.gnome.org/gnome-nightly.flatpakrepo"
+  TARBALL_ARTIFACT_PATH: ".flatpak-builder/build/${FLATPAK_MODULE}/_flatpak_build/meson-dist/${CI_PROJECT_NAME}-${CI_COMMIT_TAG}.tar.xz"
 
 stages:
   - build