Do the checklist before filing an issue:

• Is this related to the actions-rs Actions?
  If you think it's a problem related to Github Actions in general, use GitHub Community forum instead: https://github.community
• You've read the Contributing section about feature requests: https://github.com/actions-rs/.github/blob/master/CONTRIBUTING.md#feature-requests
• Is this something you can debug and fix? Send a pull request! Bug fixes and documentation fixes are welcome.

Motivation

rust-toolchain.toml is the new improved version of rust-toolchain. It also allows specifying components: https://rust-lang.github.io/rustup/overrides.html#the-toolchain-file

Workflow example

Much like rust-toolchain is auto-detected, so should the rust-toolchain.toml file. Components should be respected as well.

Thank you!