update drone.yml

drone.yml

       from_secret: reg-user
     password:
       from_secret: reg-pass
-    repo: reg.unino.de/develop/debian-${DRONE_REPO_NAME}:stable-slim
+    repo: reg.unino.de/develop/debian-${DRONE_REPO_NAME}
     #mirror: registry.hub.docker.com/library/busybox
     #bip: 172.17.0.1/24
     context: /drone
 
 
 - name: build
-  image: reg.unino.de/develop/debian-${DRONE_REPO_NAME}:stable-slim
+  image: reg.unino.de/develop/debian-${DRONE_REPO_NAME}:latest
   when:
     event: [ push, tag ]
   depends_on: [ prepare ]