Fix non-cargo dependency

Cargo.toml

@@ -25,7 +25,7 @@ heapless = "^0.5"
 
 # For nimble UUID parsing
 # see https://github.com/KokaKiwi/rust-hex/pull/42
-hex = { git = "https://github.com/Luro02/rust-hex", default_features = false }
+hex = { package = "hex-noalloc", version = "0.3.2-post1", default-features = false }
 
 coap-numbers = { version = "^0.1.0", optional = true, default-features = false }