public async Task Enqueqe(UploadItem item)
{
var name = item.File.DisplayName;
Debug.WriteLine($"Enqueqed upload {name} at {DateTime.Now}");
Uploads.Add(item);
await sem.WaitAsync();
Debug.WriteLine($"Started upload {name} at {DateTime.Now}");
await item.Upload();
Debug.WriteLine($"Finished upload {name} at {DateTime.Now}");
sem.Release();
}