Memory leak upon exiting Godot

[Nathan Lovato]

This is an issue with Godot's type system, in some cases, types can cause memory leaks.

Running Godot with the verbose option:

Leaked instance: GDScriptNativeClass:555
Leaked instance: GDScript:18650 - Resource name:  Path: res://src/GSAITargetAcceleration.gd

This happens when types reference themselves. We had that in Mannequiny: gdquest-demos/godot-3d-mannequin#30