Rails 7: use to_fs(:rfc822) for RSS pubDate (to_s(:format) no longer accepts a format in Rails 7.1+)

app/views/announcement_feeds/rssfeed.rss.builder

@@ -8,7 +8,7 @@ xml.rss :version => "2.0" do
       xml.item do
         xml.title announcement.title
         xml.description announcement.subtitle
-        xml.pubDate announcement.created_at.to_s(:rfc822)
+        xml.pubDate announcement.created_at.to_fs(:rfc822)
         xml.link page_for_bulletin(announcement)
       end
     end