Removed atom:link

The validator passes.
The mistake was in fact not missing atom:link,
but the link on image and the content-type added in
72aad6c8f8

routes/api/feeds/[seriesId].ts

@@ -36,11 +36,6 @@ async function buildFeed(seriesId: string) {
             "rss",
             [
                 tag("channel", [
-                    tag("atom:link", "", [
-                        ["href", `https://nrss.deno.dev/api/feeds/${seriesId}`],
-                        ["rel", "self"],
-                        ["type", "application/rss+xml"]
-                    ]),
                     tag("title", serie.titles.title),
                     tag("link", linkValue),
                     tag("itunes:author", "NRK"),