So, macOS 11 is unsupported and end-of-lifed by Apple as of September 26, 2023.
If you were able to install all of the dependencies under python, it should work. I am not sure how long this will last, but you are likely good for now.
I just pushed up a change to software_update.py that logs a warning rather than throws an exception. You should be able stash or undo your changes and this vesion will “just work”.