Upgrade to rand v0.9 & getrandom v0.3

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.