Update nix requirement from 0.27.1 to 0.29.0

Updates the requirements on [nix](https://github.com/nix-rust/nix) to permit the latest version.
- [Changelog](https://github.com/nix-rust/nix/blob/master/CHANGELOG.md)
- [Commits](nix-rust/nix@v0.27.1...v0.29.0)

---
updated-dependencies:
- dependency-name: nix
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

apps/Cargo.toml

@@ -30,7 +30,7 @@ octets = { version = "0.2", path = "../octets" }
 ring = "0.16"
 quiche = { path = "../quiche" }
 libc = "0.2"
-nix = { version = "0.27", features = ["net", "socket", "uio"] }
+nix = { version = "0.29", features = ["net", "socket", "uio"] }
 slab = "0.4"
 itertools = "0.10"
 clap = { version = "4.1", features = ["derive"] }