build(deps): update tokio-tungstenite requirement from 0.20 to 0.21

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] <support@github.com>

Cargo.toml

@@ -71,7 +71,7 @@ brotli = { version = "3", optional = true }
 flate2 = { version = "1", optional = true }
 
 # WebSockets
-tokio-tungstenite = { version = "0.20", optional = true, default-features = false }
+tokio-tungstenite = { version = "0.21", optional = true, default-features = false }
 sha-1 = { version = "0.10", optional = true }
 futures-util = { version = "0.3", optional = true, default-features = false, features = ["sink"] }