Fix missing inCrescendo.pop() in crescendo end listener (#5767)

The crescendo end listener pops crescendoDelta and
crescendoInitialVolume but never pops inCrescendo, causing
it to grow unboundedly and trigger spurious volume resets
on subsequent notes.

Signed-off-by: Ady0333 <adityashinde1525@gmail.com>

Author: Ady0333

js/turtleactions/VolumeActions.js

@@ -97,6 +97,8 @@ function setupVolumeActions(activity) {
                     );
                     tur.singer.crescendoInitialVolume[synth].pop();
                 }
+
+                tur.singer.inCrescendo.pop();
             };
 
             activity.logo.setTurtleListener(turtle, listenerName, __listener);