update drone-docker plugin.

Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com>

.drone.yml

@@ -57,49 +57,35 @@ pipeline:
       event: [ push, pull_request ]
       status: [ success ]
 
-  publish_latest:
-    image: plugins/docker
-    repo: ${DRONE_REPO}
-    tags: [ 'latest' ]
-    secrets: [ docker_username, docker_password ]
-    when:
-      event: [ push ]
-      branch: [ master ]
-      local: false
-
   release:
     image: appleboy/golang-testing
     pull: true
-    environment:
-      TAGS: netgo
-      GOPATH: /srv/app
     commands:
       - make release
     when:
       event: [ tag ]
-      branch: [ refs/tags/* ]
       local: false
 
-  publish_tag:
+  publish:
     image: plugins/docker
+    pull: true
     repo: ${DRONE_REPO}
-    tags: [ '${DRONE_TAG}' ]
+    default_tags: true
     secrets: [ docker_username, docker_password ]
     group: release
     when:
-      event: [ tag ]
-      branch: [ refs/tags/* ]
+      event: [ push, tag ]
       local: false
 
   release_tag:
     image: plugins/github-release
+    pull: true
     secrets: [ github_release_api_key ]
     group: release
     files:
       - dist/release/*
     when:
       event: [ tag ]
-      branch: [ refs/tags/* ]
       local: false
 
   facebook: