tests: mark unused emu fields with _

lib/tests/common/mod.rs

@@ -8,8 +8,8 @@ use gb_emu_lib::{
 
 pub struct TestEmulator {
     pub core: EmulatorCore<[u8; 4]>,
-    pub sender: Sender<EmulatorMessage<[u8; 4]>>,
-    pub audio_rx: AsyncHeapConsumer<[f32; 2]>,
+    pub _sender: Sender<EmulatorMessage<[u8; 4]>>,
+    pub _audio_rx: AsyncHeapConsumer<[f32; 2]>,
     pub serial_rx: Receiver<u8>,
 }
 
@@ -46,8 +46,8 @@ pub fn emulator_setup(rom_file: RomFile) -> Result<TestEmulator, String> {
         .map_err(|_e| String::from("Error sending message: {_e:?}"))?;
     Ok(TestEmulator {
         core,
-        sender,
-        audio_rx,
+        _sender: sender,
+        _audio_rx: audio_rx,
         serial_rx,
     })
 }