arm64

[a3s7p]

• added support for raspberry pi 4
• Update typing in fablib/installer.py.
• Use fstrings everywhere.
• accept FAB_ARCH value if set
• rename to FAB_ARCH_FAMILY & remove img support

[a3s7p]

Related to turnkeylinux/common#314 turnkeylinux/buildtasks#92

[JedMeister]

This - and turnkeylinux/common#314 & turnkeylinux/buildtasks#92 - look awesome on first glance.

As discussed offline, I'll focus on building the updated fab package first. This looks like it should have zero impact on the amd64 builds so I'll merge this now. Hopefully that shouldn't take me too long...

Once I have the updated fab done, I'll turn my attention to building the arm packages. As I mentioned, I'll ping you when I'm done. :) Once I've got on top of that, I'll probably push it back to you for a final test (and/or any further work required) and assuming that all goes good I'll test myself and we can start publishing arm builds! 🎉