Update nix package

0.23.0 fixed an issue nix-rust/nix#1545,
that `cargo deny check advisories` will fail if using the old version
of nix package.

Cargo.toml

@@ -12,7 +12,7 @@ exclude = ["test_fixture"]
 
 [dependencies]
 libc = "0.2.79"
-nix = "0.22.1"
+nix = "0.23.0"
 
 [dev-dependencies]
 rand = "0.8.3"