Using SumUp NuGet 0.0.8 with .NET 8, creating a checkout fails because Currency.Eur appears to serialize as "Eur" instead of "EUR".

Example:

var request = new CheckoutCreateRequest
{
    CheckoutReference = "test-123",
    Amount = 10.0f,
    Currency = Currency.Eur,
    MerchantCode = "<merchant-code>",
    Description = "Test order",
    ReturnUrl = "https://example.com/webhooks/sumup",
    RedirectUrl = "https://example.com/checkout/complete"
};

await client.Checkouts.CreateAsync(request);

API response:

{
  "error_code": "INVALID",
  "message": "Currency 'Eur' or amount is invalid",
  "param": "currency"
}

It looks like the SDK is using JsonStringEnumConverter(), which serializes the enum name (Eur) rather than the API value (EUR), even though the generated enum uses EnumMember(Value = "EUR").

Is this something I am missing on my side, since this would practically prevent checkouts from being created at all?