Update multiple contacts

Example request

{
  "contacts": [
    {
      "email": "elly@example.com",
      "id": 31,
      "sms": "+91xxxxxxxxxx",
      "ext_id": "UpdateExternalId",
      "attributes": {
        "EMAIL": "newemail@domain.com",
        "FNAME": "Ellie",
        "LNAME": "Roger"
      },
      "smsBlacklisted": true,
      "listIds": [
        65
      ],
      "unlinkListIds": [
        36
      ]
    }
  ]
}