use nixfmt-rfc-style to format nix code in this repo

[adrian-gierakowski]

I started working on a PR and realised that you are still using nixpkgs-fmt which has now been deprecated

[srid]

This was discussed before, but I was not convinced that nixfmt-rfc-style is better than nixpkgs-fmt.

[adrian-gierakowski]

If you have no major gripes with nixfmt-rfc-style I believe it's better to use it as it's going to be maintained while nixpkgs-fmt has been archived and is not likely to see further development.

[srid]

I do have a major gripe with it, for instance where it forces multi-line arguments whether you like it not:

---

nixpkgs-fmt has been archived and is not likely to see further development

Which has been okay with me so far.

[srid]

alejandra, or the soft fork mentioned in this doc, is another formatter to consider: ekala-project/eeps#27

Incidentally, this EEP also mentions the downsides of nixfmt-rfc-style I brought up before: