Currently needs a hack in
/var/lib/synapse/matrix-appservice-irc/node_modules/matrix-appservice-bridge/lib/components/media-proxy.js
to replace the `"http"` require with `"https"` or the proxy won't work.

See: https://github.com/matrix-org/matrix-appservice-bridge/issues/507

Mjolnir does not support Node 20.

Extend the removal of the dashes from unencrypted YAML documents to
encrypted ones as well.

Fixes: a9e0790f ("Remove the three dashes from all YAML documents")

The idea bebind this is to be able to give vault access to new DevOps
members without giving away more important credentials like Hetzner's.