Upgrade to rand v0.9 & getrandom v0.3

[Bluefinger]

Pretty straightforward PR, since rand and getrandom have new major versions, this crate should be updated to support them. I've gone and renamed various methods away from their deprecated versions to their new recommended ones (which will be compatible with Rust 2024 edition, given the gen keyword is now reserved going forward).

I also made some changes here and there to silence clippy warnings, but everything should pass the tests and compile just fine. This will necessitate publishing a new major version for fastbloom after this PR is merged.

[Bluefinger]

So, nightly removed -Zprofile and with it, the code coverage setup for this repo is broken. It's a bit of a regression on the compiler's part since it seems a lot of things are not quite there yet in terms of stabilisation, and trying to enable it requires doing digging around on how to actually do it that is a bit beyond the scope of this PR and also my expertise.

I've tried to at least make things still testable and keep coverage on what is supported, reverting to compiling/testing on stable.