List custom fields

curl --request GET \
  --url https://api.buildr.com/api/2023-01/custom_fields \
  --header 'Authorization: <authorization>'

{
  "custom_fields": [
    {
      "id": "a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a11",
      "created_at": "2023-02-14T18:13:00Z",
      "updated_at": "2023-04-03T20:16:30Z",
      "api_name": "custom_field_1",
      "category": "text",
      "model": "company",
      "name": "Custom Field 1"
    }
  ]
}