periodically update xbps

[x1ddos]

on older devices, /var/log/sysupdate.log now shows:

The 'xbps' package must be updated, please run `xbps-install -u xbps`

the idea was to set up a dedicated xbps pkg distribution and detach from the voidlinux, to be able to test combination of installed programs and only then ship updates to devices. so, a hybrid mix of a partially rolling release.