Remove dependency on removed nightly feature `array_chunks`

[bluisblu]

I get the following error when depending on this repository on rustc 1.91.0-nightly:

error[E0635]: unknown feature `array_chunks`
  --> ...\crates\hyperion\src\lib.rs:21:12
   |
21 | #![feature(array_chunks)]
   |     

This feature has been removed as not planned recently.

[kawogi]

IIUC it has been superseded by as_chunks(_mut).
This would require bumping MSRV.

[TestingPlant]

We don't currently have a MSRV, we're currently just using the nightly version from the rust-toolchain.toml and updating as needed. Thanks for mentioning the alternative, I'll keep it in mind when I get around to updating the Rust version.