Migrate to Godot 4

[goldy1992]

This custom container is very useful for many use cases so please consider these changes to allow compatibility with Godot 4.

These changes are the minimal required changes to the current code base to allow it to work on Godot 4.3.

Summary

1. Removed the private setters and getters in addons/KOBUGE-games.CircularContainer/CircularContainer.gd.
2. Migrated the _customAnimator, funcref, to use a Callable implementation.
3. deg2rad now uses deg_to_rad and vice-versa.
4. linear_interperlate is now lerp.
5. Used Godot 4.3 to automatically update the project.godot and example scenes.