Consider setting up `cargo fmt` check on CI

[zrhoffman]

Once #373 is merged and cargo fmt produces no diff, cargo fmt --check should be added to the CI.

[emilio]

Yeah, we should do this. Also cargo clippy perhaps (with relevant ignores if needed), if it doesn't get too annoying.

[l4l]

Resolved by #384?

[emilio]

Yes, indeed. Thanks!