added ship velocity using dragging volume

Game.cpp

@@ -384,6 +384,7 @@ void Game::UpdateVolumeFromMouse(int mouseX, int mouseY) {
 
     int uiX = mouseX;
     int uiY = Environment::height - mouseY;
+    Environment::shipVelocity = (musicVolume - 0.2) * (20.0);
     if (uiY < volumeBarMinY || uiY > volumeBarMaxY)
     {
         return;