update drone syntax

.drone.yml

@@ -1,9 +1,16 @@
-pipeline:
+kind: pipeline
-  docker:
+name: default
+
+steps:
+- name: docker  
   image: plugins/docker
+  settings:
     cache_from: ["shimun/mumble"]
     use_cache: true
     repo: shimun/mumble
-    secrets: ["docker_username", "docker_password"]
+    username:
+     from_secret: docker_username
+    password:
+     from_secret: docker_password