Add github action

[faddat]

This makes 2 changes:

• adds a github action that will run each time changes are made
• sets a default password, password on the nixos account (to make initial setup easier)

If you want me to take out the password part but keep the action lmk. Also feel free to copy pasta the action :)

[nvmd]

Hi! Thank you for your PR! (we'd better work this way)

There are some changes that aren't really needed, take a look at what https://github.com/nix-community/nixos-images already does.

Could you please change PR to merge into the develop and squash commits for the sake of better maintainability in the future?

[nvmd]

This additional configuration isn't needed.
This flake uses https://github.com/nix-community/nixos-images as a base for installer images:

• ssh is already enabled, permitting password logins
• root can login with the dynamically-generated password show on the screen

[faddat]

ah, thank you! I am going to put this on draft, as I do need to fix up the action :)

[umbrageodotus]

I'm gonna make my own PR. This one isn't great.