Create appointment

curl --request POST \
  --url https://connect.voxys.ai/api/v1/accounts/{account_id}/appointments \
  --header 'Content-Type: application/json' \
  --header 'api_access_token: <api-key>' \
  --data '
{
  "contact_id": 123,
  "service_id": 123,
  "provider_id": 123,
  "appointment_at": "2023-11-07T05:31:56Z",
  "notes": "<string>",
  "conversation_id": 123
}
'

{
  "id": 123,
  "contact_id": 123,
  "service_id": 123,
  "provider_id": 123,
  "appointment_at": "2023-11-07T05:31:56Z",
  "notes": "<string>",
  "cancellation_reason": "<string>",
  "conversation_id": 123,
  "created_at": "2023-11-07T05:31:56Z"
}