Get current subscription

curl --request GET \
  --url https://api.rendobar.com/billing/subscription

{
  "data": {
    "planId": "<string>",
    "status": "<string>",
    "currentPeriodStart": 123,
    "currentPeriodEnd": 123,
    "cancelAtPeriodEnd": true,
    "pendingPlanId": "<string>"
  }
}