[CI] Specify kubectl version

.drone.yml

@@ -2,9 +2,6 @@
 kind: 'pipeline'
 name: 'build'
 type: 'kubernetes'
-environment:
-  KUBE_CONFIG:
-    from_secret: 'drone_kube_config'
 
 steps:
 
@@ -12,6 +9,9 @@ steps:
 - image: 'docker.io/bitnami/kubectl'
   name: 'deploy'
   pull: 'always'
+  environment:
+    KUBE_CONFIG:
+      from_secret: 'drone_kube_config'
 
   commands:
   - 'echo $KUBE_CONFIG > $HOME/.kube/config.bin'