fix: add semi colon and clean up whitespace

src/main.rs

@@ -431,7 +431,7 @@ impl AudioVisualizer {
 
 impl Drop for AudioVisualizer {
   fn drop(&mut self) {
-    self.stop_flag.store(true, Ordering::Relaxed)
+    self.stop_flag.store(true, Ordering::Relaxed);
   }
 }