update Rust to 1.81 stable and 2024-09-08 nightly

[tzemanovic]

Describe your changes

Related CI update in https://github.com/heliaxdev/namada-ci/pull/3

Checklist before merging

• [ ] If this PR has some consensus breaking changes, I added the corresponding breaking:: labels
  • This will require 2 reviewers to approve the changes

[Fraccaman]

maybe we should use 1.80.1 ? https://blog.rust-lang.org/2024/08/08/Rust-1.80.1.html

[tzemanovic]

maybe we should use 1.80.1 ? https://blog.rust-lang.org/2024/08/08/Rust-1.80.1.html

ah yeah, I was going by releases.rs but there's some issue with it not showing

[brentstone]

what's the status here?

[tzemanovic]

what's the status here?

it needs rebased, we can also go to 1.81 now

[sug0]

can we merge this?

[brentstone]

@sug0 chatted with Tomas and decided to wait until we are ready wrt other work to cut a release, then will rebase this and merge as last PR before the release. CI is largely failing atm anyway.