[whalesalad]

this is not postgres' fault.

once the latest pgautoupgrade is available, you can do it with this:

    docker run --rm \
      -v YOUR_DATA_VOLUME:/var/lib/postgresql/data \
      -e POSTGRES_USER=USER \
      -e POSTGRES_PASSWORD=PW \
      -e POSTGRES_DB=DB \
      -e PGAUTO_ONESHOT=yes \
      pgautoupgrade/pgautoupgrade:18-bookworm

I recommend copying the volume first, in case any mistakes occur you can rollback.