Updating Python on Ubuntu 20.x
At the time of writing we can see when looking at dev-guide.python that the oldest supported version in Python 3.9 (until Nov 2025). However Ubuntu 20.x only ships with Python 3.8.
According to this stack overflow comment the easiest way to update python is as follows:
You can install python 3.9.5 in Ubuntu 20.04 even without the deadsnake PPA with the commands