Hi, how do i use the value from customers.name inside my vapi workflow as a dynamic variable? i am using below request to schedule a outbound call. curl -X POST https://api.vapi.ai/call \ -H "Authorization: Bearer " \ -H "Content-Type: application/json" \ -d '{ "workflowId": "", "customers": [ { "number": "+1 (508) 000 0000", "name": "John Doe" } ], "phoneNumberId": "" }'