HTML: Preserve playlist in "Watch on YouTube" link (#4342)

It seems that at some point, Youtube changed the URL parameter from `plid`
to `list` and we didn't notice. This fixes that.

Closes #3929

src/invidious/views/watch.ecr

@@ -118,7 +118,7 @@ we're going to need to do it here in order to allow for translations.
                     link_yt_embed = URI.new(scheme: "https", host: "www.youtube.com", path: "/embed/#{video.id}")
 
                     if !plid.nil? && !continuation.nil?
-                        link_yt_param = URI::Params{"plid" => [plid], "index" => [continuation.to_s]}
+                        link_yt_param = URI::Params{"list" => [plid], "index" => [continuation.to_s]}
                         link_yt_watch = IV::HttpServer::Utils.add_params_to_url(link_yt_watch, link_yt_param)
                         link_yt_embed = IV::HttpServer::Utils.add_params_to_url(link_yt_embed, link_yt_param)
                     end