Update tokio-tungstenite requirement from 0.20 to 0.21 (#28)

Updates the requirements on [tokio-tungstenite](https://github.com/snapview/tokio-tungstenite) to permit the latest version.
- [Changelog](https://github.com/snapview/tokio-tungstenite/blob/master/CHANGELOG.md)
- [Commits](snapview/tokio-tungstenite@v0.20.0...v0.21.0)

---
updated-dependencies:
- dependency-name: tokio-tungstenite
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

tdn/Cargo.toml

@@ -25,7 +25,7 @@ mime = "0.3"
 rand_chacha = "0.3"
 serde = { version = "1.0", default-features = false, features = ["alloc", "derive"]}
 toml = "0.8"
-tokio-tungstenite = "0.20"
+tokio-tungstenite = "0.21"
 tokio = { version = "1", features = ["full"] }
 tracing = "0.1"