修复跳过已下载文件后大小计算问题

src/N_m3u8DL-RE/Downloader/SimpleDownloader.cs

@@ -88,6 +88,7 @@ namespace N_m3u8DL_RE.Downloader
                 //已下载跳过
                 if (File.Exists(des))
                 {
+                    speedContainer.Add(new FileInfo(des).Length);
                     return new DownloadResult() { ActualContentLength = 0, ActualFilePath = des };
                 }
 
@@ -95,6 +96,7 @@ namespace N_m3u8DL_RE.Downloader
                 var dec = Path.Combine(Path.GetDirectoryName(des)!, Path.GetFileNameWithoutExtension(des) + "_dec" + Path.GetExtension(des));
                 if (File.Exists(dec))
                 {
+                    speedContainer.Add(new FileInfo(dec).Length);
                     return new DownloadResult() { ActualContentLength = 0, ActualFilePath = dec };
                 }