Latest Linux launcher provided from https://launcher.mojang.com/mc-staging/download/Minecraft_staging.deb requires libicu57 to work. Ubuntu 18.04 (which is the latest stable Ubuntu version with long term support) is shipped with libicu60.

However minecraft launcher won't launch with libicu60 as it requires libicu57:
./launcher: error while loading shared libraries: libicui18n.so.57: cannot open shared object file: No such file or directory

Creating symbolic links with the above versions also doesn't work. Please update the launcher with support for libicu60 or provide a self-contained version without any external dependencies (for instance https://snapcraft.io/).