curl --request POST \
  --url https://api.cleartalk.ai/contacts \
  --header 'Content-Type: application/json' \
  --header 'x-api-key: <api-key>' \
  --data '
{
  "listName": "<string>",
  "tag": "<string>",
  "firstName": "<string>",
  "lastName": "<string>",
  "email": "<string>",
  "phone": "<string>",
  "dateOfBirth": "<string>",
  "contactSource": "<string>",
  "clearTalkNotes": "<string>",
  "customField": {}
}
'

{
  "id": 123,
  "userId": 123,
  "listName": "<string>",
  "tag": "<string>",
  "firstName": "<string>",
  "lastName": "<string>",
  "email": "<string>",
  "phone": "<string>",
  "dateOfBirth": "<string>",
  "contactSource": "<string>",
  "clearTalkNotes": "<string>",
  "customField": {},
  "createdAt": "2023-11-07T05:31:56Z",
  "updatedAt": "2023-11-07T05:31:56Z"
}