Central Logging is just a single binary. To update you can grab a new copy at: https://www.centrallogging.com/#download unzip it, replace the old binary, and restart the service.
Or it can self-update with:
./centrallogging-linux-amd64 -update
sudo systemctl restart centrallogging
./centrallogging-openbsd-amd64 -update
doas rcctl restart syslogd
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