Fix orphaned episodes deletion (#195)

Jellyfin.Plugin.Tvdb/Providers/TvdbMissingEpisodeProvider.cs

@@ -235,6 +235,7 @@ await GetAllEpisodes(tvdbId, series.DisplayOrder, season.GetPreferredMetadataLan
             }
 
             var orphanedEpisodes = existingEpisodes
+                .Where(e => e.ParentIndexNumber == season.IndexNumber)
                 .Where(e => e.IsVirtualItem)
                 .Where(e => !seasonEpisodes.Any(episodeRecord => EpisodeEquals(e, episodeRecord)))
                 .ToList();