Update Antora base image to supported LTS release

https://gitlab.com/antora/docker-antora/-/blob/ac677ec74e7ec59fa375b07113bf6c5d90d4ea8d/Dockerfile#L1 on the current main indicates Node 16 as the current base image for the official Antora base image at https://hub.docker.com/r/antora/antora

This is long outdated, with the current LTS being Node 22 and 24. https://nodejs.org/en/about/previous-releases#release-schedule

A suggestion can be to switch to the node:lts (libc) or node:lts-alpine (musl) tag and to regularly rebuild the images upon released changes upstream.