uses outdated rust compiler version

[steven-omaha]

https://github.com/l4l/yofi/blob/master/rust-toolchain pins the rustc version to 1.64.0. The project compiles fine under 1.71.0. There seems to be no reason to pin the version.

[l4l]

It should work with any version indeed but reproducibility matters. I don't want CI lint job to be broken without explicit compiler update, nor try to remember which compiler version was used for a particular release.

I eventually update the pinned version, but users shouldn't really care about it, that's only for the devs who able modify it anyway. Formally, yofi has no MSRV but rust-toolchain could be considered as the one, i.e any version equal or greater should work fine (previous versions might also work but not guaranteed).