fix(sinaps) Fix a PHP error from sinapsConfig

Because sinaps was merged after a cleanup it was still using 1.3
 $objectclass var instead of 1.4 plObjectClass.

issue #5930

sinaps/config/sinaps/class_sinapsConfig.inc

 <?php
 /*
   This code is part of FusionDirectory (http://www.fusiondirectory.org/)
-  Copyright (C) 2017-2018 FusionDirectory
+
+  Copyright (C) 2017-2019 FusionDirectory
 
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -20,13 +21,12 @@
 
 class sinapsConfig extends simplePlugin
 {
-  var $objectclasses  = ['fdSinapsPluginConf'];
-
   static function plInfo (): array
   {
     return [
       'plShortName'     => _('SINAPS configuration'),
       'plDescription'   => _('FusionDirectory SINAPS plugin configuration'),
+      'plObjectClass'   => ['fdSinapsPluginConf'],
       'plCategory'      => ['configuration'],
       'plObjectType'    => ['smallConfig'],