Set drone context user

.drone.yml

@@ -21,6 +21,7 @@ steps:
   - name: docker release
     image: plugins/docker
     depends_on: [clone]
+    user: 0
     settings:
       username:
         from_secret: docker_username
@@ -43,6 +44,7 @@ name: build:tags
 steps:
   - name: build $DRONE_TAG
     image: plugins/docker
+    user: 0
     depends_on: [clone]
     settings:
       username:
@@ -66,6 +68,7 @@ name: build:nightly
 steps:
   - name: docker release
     image: plugins/docker
+    user: 0
     depends_on: [clone]
     settings:
       username: