[Version 1.1.0] Added Boss

First update for Spaceship! In this update, I added a boss with 2 variants. Other than that, I changed the characters and projectile sprite. Also, I tried to add particle on bullet hit too.

Added or Updated Features

• New look for the characters and projectile
• Added a boss with 2 variants
• Adjusted spawner system
• Game over screen not automatically restart the game after 5 seconds anymore