List all contacts for a customer

curl --request GET \
  --url https://eu.sequencehq.com/api/customers/{customer}/contacts \
  --header 'Authorization: <authorization>'

{
  "items": [
    {
      "id": "9a1e38a9-4dc9-776f-f974-4e7ee9f4d6cc",
      "name": "John Smith",
      "email": "john.smith@example.com",
      "billingPreference": "NONE",
      "createdAt": "2022-06-28T16:47:00Z",
      "updatedAt": "2022-06-28T16:47:00Z",
      "archivedAt": "2023-06-28T16:47:00Z"
    }
  ]
}