Use CONFIG.playlist_length_limit when exporting playlists

src/invidious/user/exports.cr

@@ -19,7 +19,7 @@ struct Invidious::User
                   json.field "privacy", playlist.privacy.to_s
                   json.field "videos" do
                     json.array do
-                      Invidious::Database::PlaylistVideos.select_ids(playlist.id, playlist.index, limit: 500).each do |video_id|
+                      Invidious::Database::PlaylistVideos.select_ids(playlist.id, playlist.index, limit: CONFIG.playlist_length_limit).each do |video_id|
                         json.string video_id
                       end
                     end