Bump nix from 0.23.0 to 0.23.1

Bumps [nix](https://github.com/nix-rust/nix) from 0.23.0 to 0.23.1.
- [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/compare/v0.23.0...v0.23.1)

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

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

Cargo.toml

@@ -90,7 +90,7 @@ wait-timeout = "0.2.0"
 tempfile = "3.2.0"
 
 [target.'cfg(unix)'.dev-dependencies]
-nix = "0.23.0"
+nix = "0.23.1"
 
 [build-dependencies]
 clap = { version = "2.34", optional = true }