Use cached images in Kubernetes pipeline

.drone.yml

@@ -14,11 +14,13 @@ trigger:
 steps:
   - name: build-image
     image: docker.m.daocloud.io/library/docker:27-cli
+    pull: if-not-exists
     commands:
       - docker build -t cdchen-frontend:k8s-${DRONE_COMMIT_SHA:0:8} .
 
   - name: deploy-k8s
     image: cdchen-k8s-tools:latest
+    pull: if-not-exists
     network_mode: teaching-k8s
     environment:
       HOME: /home/cdchen