Add build-backup CI step, include it in deploy dependencies

.drone.yml

@@ -54,9 +54,24 @@ steps:
       password:
         from_secret: gitea_password
 
+  - name: build-backup
+    image: plugins/docker
+    depends_on: [clone]
+    settings:
+      repo: git.samagsteribbe.nl/admin/dragonsstash-backup
+      registry: git.samagsteribbe.nl
+      dockerfile: backup/Dockerfile
+      tags:
+        - latest
+        - "${DRONE_COMMIT_SHA:0:8}"
+      username:
+        from_secret: gitea_username
+      password:
+        from_secret: gitea_password
+
   - name: deploy
     image: alpine
-    depends_on: [build-app, build-worker, build-bot]
+    depends_on: [build-app, build-worker, build-bot, build-backup]
     environment:
       SSH_KEY:
         from_secret: ssh_key