The URL seems to have been changed at least since several years though the exact date is unknown to me, considering the latest tagged docker image on https://hub.docker.com/r/halfshot/matrix-appservice-discord/tags (https://hub.docker.com/layers/halfshot/matrix-appservice-discord/develop/images/sha256-a1015907545603448d2d8e2ea0d31f0fdb6c7676009e2cb38e324440a9284317) is dated Feb 15, 2021.

Signed-off-by: Suguru Hirahara <acioustick@noreply.codeberg.org>