Updates feature gate to use new_zeroed_alloc

[wasv]

Needed in order to build with newest nightly

new_zeroed_alloc is a more specific version of new_uninit as introduced in:

rust-lang/rust#129396

P.S. I only noticed this because I'm trying to build dust for NixOS. Any interest in a PR to put the NixOS package definitions alongside the source itself? It'd be a nix subdirectory, a flake.nix and a flake.lock that'd be added.

[wasv]

I meant to mark this as a draft beforehand, since I haven't built it yet. Will mark as "ready for review" once I've gotten it to run.

[wasv]

At this point I've gotten it to build and almost run. I get an unrelated error due to some alsa shared libraries, but thats on my end. I also had to do some hacky stuff in my local Cargo.lock to try test it with my emu-utils PR. Once kelpsyberry/emu-utils#1 is merged though, this can be merged as well.
Only the feature gate changed, nothing logic related, so I dont know of any way to test this beyond "cargo actually lets it build now".