chore(deps): bump nix from 0.29.0 to 0.30.1 in /backend

Bumps [nix](https://github.com/nix-rust/nix) from 0.29.0 to 0.30.1.
- [Changelog](https://github.com/nix-rust/nix/blob/master/CHANGELOG.md)
- [Commits](nix-rust/nix@v0.29.0...v0.30.1)

---
updated-dependencies:
- dependency-name: nix
  dependency-version: 0.30.1
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

backend/Cargo.lock

@@ -34,7 +34,7 @@ comrak = "0.39.0"
 portable-pty = "0.8.1"
 vt100 = "0.15.2"
 bytes = "1.7.1"
-nix = { version = "0.29.0", features = ["signal"] }
+nix = { version = "0.30.1", features = ["signal"] }
 lazy_static = "1.5.0"
 shellexpand = "3.1.0"
 open = "5"