change total size diff colors (again)

[SandaruKasa]

#65 (comment)

Somewhat opinionated. If you don't vibe with it, feel free to decline.

[faukah]

Hmm, I'm not sure I like this. Red/Green is pretty unambiguous. With #101, changing the color does make more sense than before though.

I'll iterate on this a bit and try to find something that looks nice here.

[SandaruKasa]

nix store diff-closures used red for + size changes and green for - size changes. No colors for version though.