scenes/boost: stop sprite animations when the pause menu is active

sonic-boost.love/scenes/subgame/sonic-boost/controller/pause.lua

@@ -41,6 +41,7 @@ end
 function ResumeWidget:action()
   self.menu.isActive = false
   self.menu.isVisible = false
+  self.menu.controller.assets.isActive = true
 end
 
 function RestartWidget:new(menu, font)

sonic-boost.love/scenes/subgame/sonic-boost/init.lua

@@ -113,9 +113,11 @@ function BoostLevel:update(dt)
       self.menusystem.menus["pauseMenu"].isActive   = true
       self.menusystem.menus["pauseMenu"].isVisible  = true
       self.menusystem.menus["pauseMenu"]:getFocus()
+      self.assets.isActive = false
     else
       self.menusystem.menus["pauseMenu"].isActive   = false
       self.menusystem.menus["pauseMenu"].isVisible  = false
+      self.assets.isActive = true
     end
   end
 end