feat: Disable signature verification when not needed

`ring` is failing to compile for wasm targets.
Only the signature verification requires `ring` and is only useful
when either `hyper` or `axum` features are enabled.
Thus disabling signature verification and thus `ring` compilation
when neither `hyper` or `axum` are enabled.

src/lib.rs

@@ -98,6 +98,7 @@ pub mod errors;
 pub mod listener;
 mod ratectl;
 mod scroller;
+#[cfg(any(feature = "hyper", feature = "axum"))]
 pub mod signature_verifier;
 pub mod socket_mode;