Allow adding custom apt repos

[faximan]

Example: needed for apt install https://github.com/eza-community/eza/blob/main/INSTALL.md#debian-and-ubuntu.

If you add it as a script, that runs after the apt step it seems.

I guess another option is to rely on binary .deb installs.

[faximan]

"scripts": [
  "curl -sSfL https://github.com/eza-community/eza/releases/download/v0.23.4/eza_x86_64-unknown-linux-musl.tar.gz | tar xz -C ~/.local/bin --strip-components=1 --wildcards '*/eza' && chmod +x ~/.local/bin/eza"
]

works well though