fix: place ug dep behind not wasm32 flag (#2760)

* place `ug` behind not wasm32 attr

so that wasm32 can compile

* mv `ug` to conditional target dep

assuming every non-wasm32 user wants this

candle-core/src/cuda_backend/device.rs

@@ -51,6 +51,7 @@ impl CudaDevice {
         self.device.clone()
     }
 
+    #[cfg(not(target_arch = "wasm32"))]
     pub fn compile(
         &self,
         func_name: &'static str,