manifests: add back valid-subscription annotation

This was removed earlier but needs to be added back in order to pass
validation.

Signed-off-by: Jens Freimann <jfreimann@redhat.com>

config/manifests/bases/sandboxed-containers-operator.clusterserviceversion.yaml

@@ -19,6 +19,7 @@ metadata:
     operators.operatorframework.io/builder: operator-sdk-v1.20.1+git
     operators.operatorframework.io/project_layout: go.kubebuilder.io/v3
     repository: https://github.com/openshift/sandboxed-containers-operator
+    operators.openshift.io/valid-subscription: '["OpenShift Container Platform", "OpenShift Platform Plus"]'
   labels:
     operatorframework.io/arch.amd64: supported
     operatorframework.io/os.linux: supported