just upgrade

Author: wind57

spring-cloud-kubernetes-test-support/src/main/resources/current-images.txt

@@ -1,7 +1,7 @@
 busybox:1.36.1
-istio/istioctl:1.20.5
-istio/proxyv2:1.20.5
-istio/pilot:1.20.5
+istio/istioctl:1.21.6
+istio/proxyv2:1.21.6
+istio/pilot:1.21.6
 confluentinc/cp-kafka:7.2.1
 rabbitmq:3-management
 wiremock/wiremock:3.4.2