Pizza Monster updated to ver2.1

Thanks for the feedback, I have updated the game, fixed some bugs and make a little improvement.

Ver2.1 - 11 Feb, 2003
- Fixed the problem of prefabs disappeared after crashing the other randomly.
- Added game pause.
- Added background music control.
- Improved the UI elements.

Ver2.0 - 9 Feb,2023
- Discovered users can play in mobile and iPad too, so I reset the X Bound - don't let the pizza fly out of the screen even they are using mobile phone.
- Reset the collider of the prefabs, so user can click the targets properly.
- Fixed the responsive UI.