Update nix requirement from 0.27.1 to 0.28.0

Updates the requirements on [nix](https://github.com/nix-rust/nix) to permit the latest version.
- [Changelog](https://github.com/nix-rust/nix/blob/master/CHANGELOG.md)
- [Commits](nix-rust/nix@v0.27.1...v0.28.0)

---
updated-dependencies:
- dependency-name: nix
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

Cargo.toml

@@ -12,7 +12,7 @@ exclude = ["test_fixture"]
 
 [dependencies]
 libc = "0.2.150"
-nix = { version = "0.27.1", features = ["ioctl", "socket"] }
+nix = { version = "0.28.0", features = ["ioctl", "socket"] }
 
 [dev-dependencies]
 rand = "0.8.3"