public void UploadAttachment()
{
QaseAPI qaseAPI = new QaseAPI("https://api.qase.io/v1", "your api token");
var path = @"TestFiles\Test.pdf";
using var stream = new FileStream(path, FileMode.Open);
var attachment = qaseAPI.UploadAttachmentAsync("TEST", new StreamPart(stream, "test-streampart.pdf", "application/pdf")).Result;
}