Just as a first thought this appears to be a Ubuntu package manager issue, rather than something specific to BitCurator. Some of the Python tools in BitCurator depend on PyICU (which is installed by pip in the script). PyICU depends on libicu-dev (which is also installed from a package by the script). Libicu-dev has icu-devtools as a dependency (which is installed automatically by the package manager), so if that is breaking it (probably) points to the package manager being confused. You can try running "sudo apt --fix-broken install" as it suggests, or try the following and see if it helps:
sudo apt-get clean
sudo apt-get update
sudo apt-get upgrade
sudo apt install -f
For reference, I've just unpacked a fresh copy of 2.2.18, allowed it to run unattended-upgrades in the background for about an hour, restarted when prompted, and then performed a manual update with apt. I do not see this conflict appearing, so this also makes me think what you're seeing is an issue with the repository info either having been interrupted at some point (something that can happen without you doing anything, sometimes) or having gotten out of sync in some other way.
Kam