apply automated cargo clippy --fix

[yoshuawuyts]

No description provided.

[yoshuawuyts]

oh right, we're testing 1.39 in CI. Though we don't advertise an MSRV, I don't want to think about loosening that right now. Closing this now.

[yoshuawuyts]

Retrying this; apparently our deps depend on Rust 1.56 or higher - so we need to bump the CI version anyway. That's fine; updating.

[yoshuawuyts]

The reason for this patch is that #66 was just merged; and I want to make sure that the main branch has a passing CI before doing a release. That requires among other things disabling the "warnings === errors" check, and for good measure we've also applied a cargo clippy --fix pass to update the code.

[yoshuawuyts]

Seems like it needs 1.60 as a minimum. Bumped!

[yoshuawuyts]

We went from Rust 1.39 to 1.63 as a minimum. At this point we might as well drop trying to test for older Rust versions given we don't guarantee an MSRV anyway. This shouldn't break any code right now, but should at least ensure that our CI stops breaking (because our dependencies don't guarantee an MSRV either).