Remove rust-version from cargo files

[preston-evans98]

Description

Currently, all of our cargo.tomls specify a rust-version even though we have rust-toolchain.toml file. This removes that redundancy.

[codecov]

Codecov Report

Merging #1078 (553c6d9) into nightly (08e842f) will decrease coverage by 0.1%.
The diff coverage is n/a.

see 2 files with indirect coverage changes

[preston-evans98]

cc @neysofu @vlopes11, do either of you see any downsides here? I think these are just redundant, but don't remember why they were added

[neysofu]

rust-toolchain.toml specifies the intended Rust toolchain to develop the workspace in, whereas rust-version lets downstream users know the minimum required rustc version to be able to use the package.

It's a good thing to have both, but only if checked in CI with a tool like https://github.com/foresterre/cargo-msrv, otherwise rust-version will inevitably get out of sync, just like in our case. I'm in favor of removing it. It would be ideal to reintroduce it once we're confident we can provide correct values: #1081.

[vlopes11]

Agreed with @neysofu . We do enforce stable, and that should suffice for us, as stable versions will upgrade passively over time (i.e. release train).

Unless there is an explicit reason to bind ourselves to an older stable (i.e. 1.66), we shouldn't do that

[citizen-stig]

rust-toolchain.toml specifies the intended Rust toolchain to develop the workspace in, whereas rust-version lets downstream users know the minimum required rustc version to be able to use the package.

It's a good thing to have both, but only if checked in CI with a tool like https://github.com/foresterre/cargo-msrv, otherwise rust-version will inevitably get out of sync, just like in our case. I'm in favor of removing it. It would be ideal to reintroduce it once we're confident we can provide correct values: #1081.

I agree that checking MSRV is good thing, but I believe that at this moment of rapid changes of the repo it might slow as down. So I am voting to remove rust_version now and re-untroduce it later. Because with MSRV we will also have to respect MSRV of core dependencies.

[preston-evans98]

Ah, I'd forgotten this was used for MSRV checks. Yeah, we definitely need at least 1.70 already and will probably keep bumping that for a while. But agreed, let's add this back as things stabilize.