Fix instancing new Character Nodes on Simple Highlight Portrait.

This portrait is simple and allows for only one image, there is no underlying node hierarchy that may need to change.
Therefore, we need to ensure to not recreate a new character node.

addons/dialogic/Modules/HighlightPortrait/simple_highlight_portrait.gd

@@ -19,6 +19,10 @@ func _ready() -> void:
 		self.modulate = unhighlighted_color
 
 
+func _should_do_portrait_update(_character: DialogicCharacter, _portrait: String) -> bool:
+    return true
+
+
 func _highlight() -> void:
 	create_tween().tween_property(self, 'modulate', Color.WHITE, 0.15)
 	_prev_z_index = DialogicUtil.autoload().Portraits.get_character_info(character).get('z_index', 0)