Riggy cat for Godot 4 (spine-godot 4.2)

1. Download the spine-godot GDExtension built for Spine 4.2 and your Godot version,
   and copy its bin/ folder here, next to project.godot.
2. Open project.godot in the Godot editor; it imports the Spine files on the first
   open. Importing from a terminal instead (CI, build scripts)? Run
   godot --headless --path . --import two times: the first pass only registers
   the extension, the Spine files import on the second.
3. Run the project. Click to play the next animation.

Guide: https://riggyapp.com/blog/godot-spine-animation-from-psd
Shipping a game with the Spine Runtimes requires a Spine license from Esoteric
Software: https://riggyapp.com/licensing
