bump cuby image to 0.6.0-develop.6

Author: Robin Lenz

hetzner-setup/ProcessCube.Cloud/ansible/roles/install_cuby/templates/cuby-operator.yaml.j2

@@ -127,7 +127,7 @@ spec:
         - name: regcred
       containers:
         - name: cuby
-          image: marketplace.processcube.io/5minds/cuby:0.6.0-develop.4
+          image: marketplace.processcube.io/5minds/cuby:0.6.0-develop.6
           imagePullPolicy: Always
           ports:
             - name: http