Upgrade to bookworm broke things with the new nut-server pkg

The error is misleading - it has to do with some debug code.

Some details on the mailing list at:
https://alioth-lists.debian.net/pipermail/nut-upsuser/2023-July/013366.html

The jist of it - the driver upscode2 works with debug=3 - but not without - some
bug was just fixed that probably cures this according to the mailing list.

I didn't sucseed in creating a new pkg from the github sources so I downgraded to the
old version to keep things working.

There is a new version upstream - would love to test it once in a deb package.