List all countries

curl --request GET \
  --url https://api.notchpay.co/countries \
  --header 'Authorization: <api-key>'

{
  "code": 200,
  "status": "OK",
  "message": "Countries retrieved",
  "items": [
    {
      "name": "Cameroun",
      "code": "CM"
    }
  ]
}