update Cargo edition & dependencies versions

[imrn99]

Content of the PR:

• update to 2024 edition & remove the format file which pinned the edition to 2021
  • format with new edition standards
• add taplo config file for toml formatting
  • format toml files
• update dependencies to latest versions (excluding rc releases)
  • nalgebra and rand required code changes for builds to succeed, so I made those and ignored other clippy lints, which I can process in a separate PR
• pin deps to their exact versions

Concerning the flake:

• I added it because that's how I like to get my toolchain, but I can remove it if desired
• If we keep both the flake and the Cargo.lock file, I can add a check target to the flake that runs all usual tests (format, lints)
• removed

CI:

• I'd like to handle all clippy lints in a dedicated PR, after update CI #318 and this one are merged
• coverage fails because the current workflow didn't use a token for auth to codecov, they probably changed their rate / policy for tokenless usage. update CI #318 fixes it

[imrn99]

I just noticed the root manifest defines workspace members AND is used for the coupe library. Dependencies defined there aren't reused by members, which created some version mismatches.

I'll match the version manually for now and clean the workspace structure separately if that's ok @cedricchevalier19

[cedricchevalier19]

I am in favour to allow regular lock and not to require using nix flakes.

I'll look at the PR soon.