build(deps): bump nix from 0.26.2 to 0.26.4

Bumps [nix](https://github.com/nix-rust/nix) from 0.26.2 to 0.26.4.
- [Changelog](https://github.com/nix-rust/nix/blob/v0.26.4/CHANGELOG.md)
- [Commits](nix-rust/nix@v0.26.2...v0.26.4)

---
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

@@ -107,7 +107,7 @@ zstd = "0.13"
 
 # dist-server only
 memmap2 = "0.9.0"
-nix = { version = "0.26.2", optional = true }
+nix = { version = "0.26.4", optional = true }
 object = "0.30"
 rouille = { version = "3.6", optional = true, default-features = false, features = [
   "ssl",