Update hostname requirement from 0.3.0 to 0.4.0

Updates the requirements on [hostname](https://github.com/svartalf/hostname) to permit the latest version.
- [Release notes](https://github.com/svartalf/hostname/releases)
- [Changelog](https://github.com/svartalf/hostname/blob/master/CHANGELOG.md)
- [Commits](svartalf/hostname@v0.3.0...v0.4.0)

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

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

server/Cargo.toml

@@ -19,7 +19,7 @@ serde = { version = "1.0.104", features = ["derive", "rc"] }
 toml = { workspace = true }
 anyhow = "1.0.26"
 rcgen = { version = "0.12.1", default-features = false, features = ["ring"] }
-hostname = "0.3.0"
+hostname = "0.4.0"
 futures = "0.3.1"
 hecs = { workspace = true }
 rand = { version = "0.8.5", features = ["small_rng"] }