Add dyn to the traits

This fixes a few warnings on nightly

src/dynamic_mixer.rs

@@ -41,7 +41,7 @@ where
 /// The input of the mixer.
 pub struct DynamicMixerController<S> {
     has_pending: AtomicBool,
-    pending_sources: Mutex<Vec<Box<Source<Item = S> + Send>>>,
+    pending_sources: Mutex<Vec<Box<dyn Source<Item = S> + Send>>>,
     channels: u16,
     sample_rate: u32,
 }
@@ -68,7 +68,7 @@ where
 /// The output of the mixer. Implements `Source`.
 pub struct DynamicMixer<S> {
     // The current iterator that produces samples.
-    current_sources: Vec<Box<Source<Item = S> + Send>>,
+    current_sources: Vec<Box<dyn Source<Item = S> + Send>>,
 
     // The pending sounds.
     input: Arc<DynamicMixerController<S>>,

src/queue.rs

@@ -48,7 +48,7 @@ where
 
 /// The input of the queue.
 pub struct SourcesQueueInput<S> {
-    next_sounds: Mutex<Vec<(Box<Source<Item = S> + Send>, Option<Sender<()>>)>>,
+    next_sounds: Mutex<Vec<(Box<dyn Source<Item = S> + Send>, Option<Sender<()>>)>>,
 
     // See constructor.
     keep_alive_if_empty: AtomicBool,
@@ -98,7 +98,7 @@ where
 /// The output of the queue. Implements `Source`.
 pub struct SourcesQueueOutput<S> {
     // The current iterator that produces samples.
-    current: Box<Source<Item = S> + Send>,
+    current: Box<dyn Source<Item = S> + Send>,
 
     // Signal this sender before picking from `next`.
     signal_after_end: Option<Sender<()>>,

src/source/mod.rs

@@ -302,7 +302,7 @@ where
     }
 }
 
-impl<S> Source for Box<Source<Item = S>>
+impl<S> Source for Box<dyn Source<Item = S>>
 where
     S: Sample,
 {
@@ -327,7 +327,7 @@ where
     }
 }
 
-impl<S> Source for Box<Source<Item = S> + Send>
+impl<S> Source for Box<dyn Source<Item = S> + Send>
 where
     S: Sample,
 {
@@ -352,7 +352,7 @@ where
     }
 }
 
-impl<S> Source for Box<Source<Item = S> + Send + Sync>
+impl<S> Source for Box<dyn Source<Item = S> + Send + Sync>
 where
     S: Sample,
 {