Update quay.io/appuio/oc Docker tag to v4.21

Signed-off-by: Renovate Bot <tech+renovate@vshn.ch>

Author: vshn-renovate

class/defaults.yml

@@ -7,7 +7,7 @@ parameters:
       oc:
         registry: quay.io
         repository: appuio/oc
-        tag: v4.20
+        tag: v4.21
 
     namespace: openshift-console
     namespace_annotations: