build docker image `manual`

.drone.yml

@@ -10,12 +10,13 @@ steps:
   - go test ./...
 
 - name: publish
-  image: plugins/docker
-  settings:
-    auto_tag: true
-    repo: garionion/drone-yaml-server
+  image: docker:20
+  environment:
     username:
       from_secret: docker_username
     password:
       from_secret: docker_password
-    debug: true
+  commands:
+    - docker login -u $username --password $password
+    - docker build --tag drone-yaml-server:latest $PWD
+    - docker push drone-yaml-server:latest