Bump nix from 0.29.0 to 0.30.1

Bumps [nix](https://github.com/nix-rust/nix) from 0.29.0 to 0.30.1.
- [Changelog](https://github.com/nix-rust/nix/blob/master/CHANGELOG.md)
- [Commits](nix-rust/nix@v0.29.0...v0.30.1)

---
updated-dependencies:
- dependency-name: nix
  dependency-version: 0.30.1
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

Cargo.lock

@@ -71,7 +71,7 @@ plist = "1.7.0"
 parking_lot = "0.12.2"
 num_cpus = "1.13.1"
 uname = "0.1.1"
-nix = { version = "0.29", features = ["fs", "process"] }
+nix = { version = "0.30", features = ["fs", "process"] }
 os-release = "0.1.0"
 
 [target.'cfg(windows)'.dependencies]