curl --request GET \
  --url https://api.stackone.com/unified/crm/custom_field_definitions/contacts \
  --header 'Authorization: Basic <encoded-value>' \
  --header 'x-account-id: <x-account-id>'

{
  "next_page": "<string>",
  "next": "<string>",
  "data": [
    {
      "id": "8187e5da-dc77-475e-9949-af0f1fa4e4e3",
      "remote_id": "8187e5da-dc77-475e-9949-af0f1fa4e4e3",
      "name": "<string>",
      "description": "<string>",
      "type": "Dropdown",
      "options": [
        {
          "id": "option_1",
          "value": "Not Started"
        },
        {
          "id": "option_2",
          "value": "In Progress"
        },
        {
          "id": "option_3",
          "value": "Completed"
        }
      ]
    }
  ],
  "raw": [
    {
      "method": "<string>",
      "url": "<string>",
      "body": "<string>",
      "response": {}
    }
  ]
}