curl --request POST \
  --url https://api.onset.io/v1/subscribers \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '{
  "email": "jsmith@example.com",
  "list_ids": [
    "3c90c3cc-0d44-4b50-8888-8dd25736052a"
  ]
}'

{
  "id": "<string>",
  "email": "jsmith@example.com",
  "lists": [
    {
      "id": "<string>",
      "name": "<string>"
    }
  ],
  "created_at": "2023-11-07T05:31:56Z",
  "updated_at": "2023-11-07T05:31:56Z"
}