public async Task<IEnumerable<VersionDescription>> CheckVersionTaskAsync(CancellationToken cancel_token)
{
var results = await appcastReader.DownloadVersionInfoTaskAsync(url, cancel_token);
if (results==null) return null;
return results
.Where(v => v.PublishDate.Date>currentVersion)
.OrderByDescending(v => v.PublishDate);
}