Fix missing comma

modules/gdscript/gd_script.cpp

@@ -2696,7 +2696,7 @@ void GDScriptLanguage::get_reserved_words(List<String> *p_words) const  {
 		"class",
 		"extends",
 		"func",
-		"preload"
+		"preload",
 		"setget",
 		"signal",
 		"tool",