fix: set correct field in MietteHandlerOpts::ansi_colors

[sunshowers]

Thanks for miette! We've been having a great time using it in
cargo-nextest to print out nicely-formatted errors.

I noticed a bug while testing out miette -- the ansi_colors method
does not set ANSI colors properly.

By the way, I do not believe miette should use RGB colors at all --
default colors in applications must be restricted to 12 ANSI colors. See
https://rust-cli-recommendations.sunshowers.io/colors.html#color-palettes
for why. I'm happy to disable RGB colors in all the applications I
maintain, but doing so globally is something for upstream to consider.

[zkat]

wow, copy/paste is incredibly rude. Absolutely terrible.

Thanks for this patch!

[zkat]

also re: ansi colors

That's a pity, re: ansi colors! I spent a good amount of time making sure the default colors were both attractive and colorblindness friendly, both of which I think the default ANSI color set kinda... fails to do in most cases.

That said, perhaps you're right and it shouldn't be the default. I'd be happy to take a patch that makes ANSI the default, but the specifics might warrant some discussion. Happy to see a concrete proposal, though!

[sunshowers]

Thanks for considering the change to ANSI colors!

That's a pity, re: ansi colors! I spent a good amount of time making sure the default colors were both attractive and colorblindness friendly, both of which I think the default ANSI color set kinda... fails to do in most cases.

I think that is definitely true for the default color scheme in most terminals, but the benefit of them is that users can customize them arbitrarily. I would imagine that most colorblind users would have set up an appropriate theme already (though I don't have data to support this!).

I think (as in the color palette link from my recommendations above) that the benefit of being able to customize colors in a global fashion is precisely the benefit that ANSI colors offer and that's harder to access with RGB colors.