List card scheme definitions

using Gr4vy;
using Gr4vy.Models.Components;

var sdk = new Gr4vySDK(
    id: "example",
    server: SDKConfig.Server.Sandbox,
    bearerAuthSource: Auth.WithToken(privateKey),
    merchantAccountId: "default"
);

var res = await sdk.CardSchemeDefinitions.ListAsync();

// handle response

{
  "items": [
    {
      "type": "card-scheme-definition",
      "id": "visa",
      "icon_url": "https://api.sandbox.example.gr4vy.app/assets/card-scheme-definitions/visa.svg",
      "display_name": "Visa"
    }
  ]
}