build(deps): update nix requirement from 0.15.0 to 0.16.0

Updates the requirements on [nix](https://github.com/nix-rust/nix) to permit the latest version.
- [Release notes](https://github.com/nix-rust/nix/releases)
- [Changelog](https://github.com/nix-rust/nix/blob/master/CHANGELOG.md)
- [Commits](https://github.com/nix-rust/nix/commits/v0.16.0)

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

heim-common/Cargo.toml

@@ -23,7 +23,7 @@ uom = { version = "0.26.0", default-features = false, features = ["autoconvert",
 
 [target.'cfg(unix)'.dependencies]
 libc = "~0.2"
-nix = "0.15.0"
+nix = "0.16.0"
 lazy_static = "1.3.0"
 
 [target.'cfg(target_os = "windows")'.dependencies]

heim-net/Cargo.toml

@@ -28,7 +28,7 @@ futures-executor = "^0.3"
 version-sync = "0.8"
 
 [target.'cfg(unix)'.dependencies]
-nix = "0.15.0"
+nix = "0.16.0"
 
 [target.'cfg(target_os = "linux")'.dependencies]
 hex = "0.4.0"