Switch to `rustix`?

[Krysztal112233]

Recently I introduced rustix for refactoring and optimizing the code of pgrep because of I found that nix crate doesn't supported statx syscall butrustix do.

After relative pr has been merged, I think maybe nix and rustix keeping just one of them is sufficient, because it overlaps significantly.

But I'm worried that replacing nix with rustix might cause some unexpected issues, after all, rustix is still very young.

I wonder if anyone has any related thoughts :)

cc @cakebaker @sylvestre @dezgeg @Bluemangoo @tertsdiepraam

[Krysztal112233]

And what attracts me most about rustix is that it provides Rust-style calls and focuses on type safety and IO safety.