How do up upgrade LetsEncrypt certbot to version 0.22 which supports wildcard certificates?
If you have already installed Certbot, you should add a parameter to apt-get install to upgrade only a specific package
sudo apt-get update
sudo apt-get install --only-upgrade certbot
Check version number
certbot --version || /path/to/certbot-auto --version
Reference answer: How to upgrade a single package using apt-get?
As the certbot site indicates, the certbot team maintains a PPA. The certbot package is at 0.22.2 on all supported versions of Ubuntu in that PPA. (What are PPAs and how do I use them?)