Correct typo in wasm feature flag

Author: cjpearce

src/native.rs

@@ -3,5 +3,5 @@
 #[cfg(all(feature = "curl_client", not(target_arch = "wasm32")))]
 pub use super::isahc::IsahcClient as NativeClient;
 
-#[cfg(all(feature = "wasm-client", target_arch = "wasm32"))]
+#[cfg(all(feature = "wasm_client", target_arch = "wasm32"))]
 pub use super::wasm::WasmClient as NativeClient;