upgrade to bind 9.21

build-bind.jenkins

@@ -132,7 +132,7 @@ fi
                     writeFile(file: workspace + "/test-chamber-13.lan.root.crt", text: functions.getCurrentRootCA())
 
                     dockerFile = """
-FROM ${repository}/dockerhub/internetsystemsconsortium/bind9:9.18
+FROM ${repository}/dockerhub/internetsystemsconsortium/bind9:9.21
 
 LABEL org.opencontainers.image.authors="The_Spider <spider@smoothnet.org>"
 LABEL org.opencontainers.image.title="bind"