Add "force_tag" setting to build config

.drone.yml

@@ -13,8 +13,9 @@ steps:
     settings:
       registry: docker.dietrich-rink.de
       repo: docker.dietrich-rink.de/drone-test
-      tags: latest
       auto_tag: true
+      tags: latest
+      force_tag: true
       username:
         from_secret: registry_user
       password: