Update Rust crate tokio-tungstenite to 0.26

Author: oxide-renovate[bot]

Cargo.toml

@@ -34,7 +34,7 @@ propolis-server-config = { git = "https://github.com/oxidecomputer/propolis", re
 toml = "0.7"
 libc = "0.2"
 tokio = { version = "1.44.1", features = ["full"] }
-tokio-tungstenite = "0.21"
+tokio-tungstenite = "0.26"
 futures = "0.3"
 clap = { version = "4.0.28", features = ["color", "derive"] }
 tabwriter = { version = "1", features = ["ansi_formatting"] }