fixing string encoding issue in rss enclosure length attribute

rss.go

@@ -76,7 +76,7 @@ type RssEnclosure struct {
 	//RSS 2.0 <enclosure url="http://example.com/file.mp3" length="123456789" type="audio/mpeg" />
 	XMLName xml.Name `xml:"enclosure"`
 	Url     string   `xml:"url,attr"`
-	Length  string   `xml:"length,attr"`
+	Length  int64    `xml:"length,attr"`
 	Type    string   `xml:"type,attr"`
 }
 
@@ -91,7 +91,7 @@ func newRssItem(i *Item) *RssItem {
 		Link:        i.Link.Href,
 		Description: i.Description,
 		Guid:        i.Id,
-		Enclosure:   &RssEnclosure{Url: i.Link.Href, Type: i.Link.Type, Length: string(i.Link.Length)},
+		Enclosure:   &RssEnclosure{Url: i.Link.Href, Type: i.Link.Type, Length: i.Link.Length},
 		PubDate:     anyTimeFormat(time.RFC822, i.Created, i.Updated),
 	}
 	if i.Author != nil {