Unfortunately Linux Mint, as well as some other Ubuntu derivatives, has applied a rule that the command to update inxi is blocked by default. This means that all Linux Mint users, and users of any other Ubuntu derivatives, are using an outdated version of the inxi terminal command line tool. However, there's a fix available to undo this blockage to update the inxi tool.
This solution works straight away but needs some manual tweaking:
Open a terminal
Type or copy/paste) the following command in the terminal:
gksudo gedit /etc/inxi.conf
(replace gedit with leafpad or pluma or any other text editor you're using)
At the bottom replace:
B_ALLOW_UPDATE=false
with:
B_ALLOW_UPDATE=true
Save and close the file
After closing the file the following command can be run in a terminal to update inxi:
sudo inxi -U