Allow cloning SPIRC

- which is just a tokio::sync::mpsc sender, so this should be safe
- prep for MPRIS support, which will use this to control playback

connect/src/spirc.rs

@@ -160,6 +160,7 @@ const CONTEXT_FETCH_THRESHOLD: u32 = 5;
 const VOLUME_STEPS: i64 = 64;
 const VOLUME_STEP_SIZE: u16 = 1024; // (u16::MAX + 1) / VOLUME_STEPS
 
+#[derive(Clone)]
 pub struct Spirc {
     commands: mpsc::UnboundedSender<SpircCommand>,
 }