Replaced deprecated "get" cs func in fps tutorial

In the 3D fps tutorial, changed the camera global transform
function to use direct property setting instead of getter
since the getter is deprecated in 3.2.1.

tutorials/3d/fps_tutorial/part_one.rst

@@ -290,7 +290,7 @@ Add the following code to ``Player.gd``:
             //  -------------------------------------------------------------------
             //  Walking
             _dir = new Vector3();
-            Transform camXform = _camera.GetGlobalTransform();
+            Transform camXform = _camera.GlobalTransform;
 
             Vector2 inputMovementVector = new Vector2();