project: create set stack-ref to null

[talset]

OLD_PROJECT=oldproject
OLD_PROJECT_DETAIL=$(cy project get -o json --project $OLD_PROJECT)

# Create the new project
NEW_PROJECT=newproject
cy project create \
  --name $NEW_PROJECT \
  --description "$(echo $OLD_PROJECT_DETAIL | jq -r .description)" \
  --stack-ref $(echo $OLD_PROJECT_DETAIL | jq -r .service_catalog.ref) \
  --config-repo $(echo $OLD_PROJECT_DETAIL | jq -r .config_repository_canonical)