Fix for embedding thumbnail in mp3 by pauldubois98

Authored-by: Paul Dubois <pauldubois98@gmail.com>

youtube_dlc/postprocessor/embedthumbnail.py

@@ -76,8 +76,8 @@ class EmbedThumbnailPP(FFmpegPostProcessor):
 
         if info['ext'] == 'mp3':
             options = [
-                '-c', 'copy', '-map', '0', '-map', '1',
-                '-metadata:s:v', 'title="Album cover"', '-metadata:s:v', 'comment="Cover (Front)"']
+                '-c', 'copy', '-map', '0:0', '-map', '1:0', '-id3v2_version', '3', 
+                '-metadata:s:v', 'title="Album cover"', '-metadata:s:v', 'comment="Cover (front)"']
 
             self._downloader.to_screen('[ffmpeg] Adding thumbnail to "%s"' % filename)