Update workflow

[swsnr]

• Replace actions-rs/toolchain which is unmaintained.
• Update checkout action.
• Remove names from all steps, to shorten the workflow definition.

[swsnr]

@lucab I've removed the names from all steps, because they mostly repeated the command name anyway. It makes the workflow definition shorter without loosing anything, in my opinion, but if you dislike this change, I'll rebase it out 🙂

[swsnr]

@lucab You're welcome 🙏🏿