Update game examples to work with ruby2d-0.12.1

[StevenH34]

Changes made

Helps resolve #7

Games would not execute. Encountered errors loading text and font file:

• .../ruby2d-0.12.1/lib/ruby2d/text.rb:25:in 'initialize': wrong number of arguments (given 0, expected 1)
• Cannot find font file ../fonts/Ubuntu.ttf

The examples color-dodge, keyevent-example, and triangle-game all run now on ruby2d-0.12.1. Code was updated on MacOS 15.2.