* Start adding CMSIS MCU description tool
* Add 'add-missing'
* Switch MCU descriptions to JSON5
* Add new MCU after rebase
* Use virtualenv instead of APT for installing packages
* Also remove apt requirements files
* Wrong command!
* Check if index file exists before checking update time
* Respond to comments
* Make must_exist keyword only
---------
Co-authored-by: Victor Tang <me@victorwtang.dev>
Jamie Smith