curl --request GET \
  --url https://api.proficientai.com/users \
  --header 'Key: <api-key>'

{
  "data": [
    {
      "id": "<string>",
      "object": "user",
      "created_at": 123,
      "external_id": "<string>",
      "first_name": "<string>",
      "last_name": "<string>",
      "live_mode": true,
      "updated_at": 123
    }
  ]
}