Remove useless auto_generated param from PlaylistVideo#to_xml

given the variables available in this function's context, 'author' and 'ucid'
provide the same data 'self.author' and 'self.ucid', respectively.

Given that fact, the variable `auto_generated` has no impact on the logic of
this function, and hence can be safely removed. this greatly simplifies the
code and makes it perfectly compatible with crystal's calling convention for
'#to_xml' methods.

src/invidious/routes/feeds.cr

@@ -281,9 +281,7 @@ module Invidious::Routes::Feeds
               xml.element("name") { xml.text playlist.author }
             end
 
-            videos.each do |video|
-              video.to_xml(false, xml)
-            end
+            videos.each &.to_xml(xml)
           end
         end
       else