curl --request GET \
  --url https://api.loopreturns.com/api/v1/customers \
  --header 'X-Authorization: <api-key>'

{
  "customers": [
    {
      "id": 123,
      "external_id": "<string>",
      "channel": "<string>",
      "first_name": "<string>",
      "last_name": "<string>",
      "email": "[email protected]",
      "phone": "<string>",
      "tags": [
        "<string>"
      ]
    }
  ],
  "next_page_url": "<string>",
  "previous_page_url": "<string>"
}