curl --request PUT \
  --url https://api.steppay.kr/api/v1/subscriptions/{subscriptionId}/interval \
  --header 'Content-Type: application/json' \
  --header 'Secret-Token: <api-key>' \
  --data '
{
  "interval": "DAY",
  "intervalCount": 123
}
'

{
  "message": "<string>",
  "body": {}
}