CI: Use actions-rust-lang/setup-rust-toolchain

[RytoEX]

Description

CI: Use actions-rust-lang/setup-rust-toolchain

Replace actions-rs/toolchain with actions-rust-lang/setup-rust-toolchain since the former is deprecated/archived and is throwing CI warnings.

Motivation and Context

Want less CI warnings.

Key points:

1. actions-rust-lang/setup-rust-toolchain no longer exposes profile or override as options. If you want to set profile to minimal, you must provide a rust toolchain file.
2. actions-rust-lang/setup-rust-toolchain seems to include Swatinum/rust-cache and will use it if you specify cache to the action. This can probably be addressed later, if desired.
   https://github.com/actions-rust-lang/setup-rust-toolchain/blob/b113a30d27a8e59c969077c0a0168cc13dab5ffc/action.yml#L174-L178

The initial run took longer than usual runs here, but that seems to have been due to the lack of cache. A subsequent run was comparable to run times here.
https://github.com/RytoEX/bouf/actions/runs/8726305940

How Has This Been Tested?

Tested on my fork.

Types of changes

• Tweak (non-breaking change to improve existing functionality)

• Code cleanup (non-breaking change which makes code smaller or more readable)

Checklist:

• My code has been run through clang-format.
• I have read the contributing document.
• My code is not on the master branch.
• The code has been tested.
• All commit messages are properly formatted and commits squashed where appropriate.
• I have included updates to all appropriate documentation.