chore(drone): always pull image

Author: duanhongyi

.drone/drone.yml

@@ -5,7 +5,7 @@ name: default
 steps:
 - name: test
   image: docker.io/drycc/go-dev
-  pull: if-not-exists
+  pull: always
   privileged: true
   commands:
   - VERSION=${DRONE_TAG:-latest} make test 
@@ -23,7 +23,7 @@ steps:
 
 - name: build
   image: docker.io/drycc/go-dev
-  pull: if-not-exists
+  pull: always
   privileged: true
   commands:
   - VERSION=${DRONE_TAG:-latest} make build