Update .drone.yml

.drone.yml

@@ -6,7 +6,8 @@ steps:
   - name: debug registry secrets
     image: alpine
     commands:
-      - echo "$${docker_username}"
+      - echo "Username: $${docker_username}"
+      - echo "$${docker_password}" | wc -c
 
   - name: build and push flappy image
     image: plugins/docker