Adding a require to /etc/apt/listchanges.conf for the package
apt-listchanges so that listchanges.conf doesn't get added before the
listchanges package is installed causing apt to hit a catch 22.

Add an if statement to 50unattended-upgrades so that Debian doesn't
get Unattended-Upgrade::Allowed-Origins which doesn't work and causes
unattended upgrades to stop.