build docker image manual

.drone.yml

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