metrics-server: Update to version v0.7.2-master-18

Update container-registry.zalando.net/teapot/metrics-server to version v0.7.2-master-18

Author: zalando-teapot-robot

cluster/manifests/metrics-server/deployment.yaml

@@ -28,7 +28,7 @@ spec:
       serviceAccountName: metrics-server
       containers:
       - name: metrics-server
-        image: container-registry.zalando.net/teapot/metrics-server:v0.7.0-master-16
+        image: container-registry.zalando.net/teapot/metrics-server:v0.7.2-master-18
         args:
         - --cert-dir=/tmp
         - --secure-port=4443