Normally I do not shut down services in order to perform updates, but the new Lemmy release requires a newer version of the PostgreSQL database server, which in turn requires a migration of the very cluster. If nothing special is hindering it (this happened with the Synapse Matrix server recently), this will be done quite quickly by just linking to the newer Postgres version (this is a feature of Postgres itself), otherwise it might take an hour or two.
This will also affect the Firefish microblogging instance under https://procial.tchncs.de
16:00 UTC, so in about 4½ hours