chore: Release nix version 0.26.4

Author: asomers

CHANGELOG.md

@@ -3,7 +3,7 @@
 All notable changes to this project will be documented in this file.
 This project adheres to [Semantic Versioning](https://semver.org/).
 
-## [Unreleased] - ReleaseDate
+## [0.26.4] - 2023-08-28
 
 ### Fixed
 

Cargo.toml

@@ -2,7 +2,7 @@
 name        = "nix"
 description = "Rust friendly bindings to *nix APIs"
 edition     = "2018"
-version     = "0.26.3"
+version     = "0.26.4"
 rust-version = "1.56"
 authors     = ["The nix-rust Project Developers"]
 repository  = "https://github.com/nix-rust/nix"