Package 'libtinfo5' has no installation candidate
Solution 1:
At first you have to fix the GPG problem with GitHub CLI repository by using commands below:
sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-key C99B11DEB97541F0
Then disable cdrom source by editing /etc/apt/sources.list by text editor directly or by using Software & Updates (software-properties-gtk) application.
Then add the universe repository pocket to the system by the same application or by using command
sudo add-apt-repository universe
And finally update package lists and install needed package:
sudo apt-get update
sudo apt-get install libtinfo5