Add compatibility code for CSGBox3D width/height/depth from Godot 3.x

Fixes #66420.

modules/csg/csg_shape.h

@@ -248,6 +248,10 @@ class CSGBox3D : public CSGPrimitive3D {
 
 protected:
 	static void _bind_methods();
+#ifndef DISABLE_DEPRECATED
+	// Kept for compatibility from 3.x to 4.0.
+	bool _set(const StringName &p_name, const Variant &p_value);
+#endif
 
 public:
 	void set_size(const Vector3 &p_size);