chore: bump nix dependency to 0.31.3

Address review feedback requesting the latest nix crate version.

Cargo.lock

@@ -3258,9 +3258,9 @@ checksum = "27b02d87554356db9e9a873add8782d4ea6e3e58ea071a9adb9a2e8ddb884a8b"
 
 [[package]]
 name = "nix"
-version = "0.30.1"
+version = "0.31.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "74523f3a35e05aba87a1d978330aef40f67b0304ac79c1c00b294c9830543db6"
+checksum = "cf20d2fde8ff38632c426f1165ed7436270b44f199fc55284c38276f9db47c3d"
 dependencies = [
  "bitflags 2.13.0",
  "cfg-if",

Cargo.toml

@@ -61,7 +61,7 @@ unstable = []
 # Logging
 syslog = "7.0.0"
 # Filesystem access checks (e.g. sendmail executability for the current user)
-nix = { version = "0.30.1", default-features = false, features = ["fs"] }
+nix = { version = "0.31.3", default-features = false, features = ["fs"] }
 
 [dependencies]
 macros = { path = "./macros" }