Bump nix from 0.27.1 to 0.28.0

Bumps [nix](https://github.com/nix-rust/nix) from 0.27.1 to 0.28.0.
- [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
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

Cargo.toml

@@ -12,7 +12,7 @@ gethostname = "0.4"
 hostname = { version = "0.3", features = ["set"] }
 ipnet = "2.8"
 log = "0.4"
-nix = { version = "0.27", features = ["reboot"] }
+nix = { version = "0.28", features = ["reboot"] }
 pnet = { version = "0.34", features = ["pnet_datalink", "std"] }
 regex = "1.9"
 serde = { version = "1", features = ["derive"] }