Update Rust crate axum to 0.8

Author: renovate[bot]

hal/uart-kble/Cargo.toml

@@ -10,7 +10,7 @@ once_cell = "1"
 futures = "0.3"
 kble-socket = { version = "0.3.0", features = ["axum"] }
 tokio = { version = "1", features = ["sync", "rt"] }
-axum = { version = "0.6", default-features = false, features = ["tokio", "http1", "ws"] }
+axum = { version = "0.8", default-features = false, features = ["tokio", "http1", "ws"] }
 anyhow = "1"
 
 [dev-dependencies]