use default cargo instead of github action

[andrewbanchich]

not sure if you're aware, but cargo is installed by default on github action runners, so AFAIK there is no need to use actions like the one your action is using. i'd be interested in if there's a valid use case for it i'm not aware of, but if there isn't it would be good to just run: cargo install cargo-machete.

[bnjbvr]

Yeah, no good reason I think, thanks for the heads-up! Would you like to open a pull-request?