gajim-nightly from FTP is missing python3-nbxmpp >= 0.9.94 - Ubuntu 19.10/20.04
For a few days now, the latest gajim-nightly from the FTP repository can't be installed in Ubuntu 19.10. It's complaining about the python3-nbxmpp >= 0.9.94 not being available.
The one on your FTP is 0.6.10-1. See https://ftp.gajim.org/debian/dists/unstable/main/binary-amd64/Packages .
Ubuntu 19.10 also only has 0.6.10-1. Ubuntu 20.04 comes with 0.6.10-1.1 which also doesn't match. Maybe you can provide the newer version on your FTP?