Fixed php8 warning

dataprocessor.php

@@ -162,12 +162,7 @@ function dataprocessor_civicrm_config(&$config) {
     $template =& CRM_Core_Smarty::singleton();
     $extRoot = dirname(__FILE__) . DIRECTORY_SEPARATOR;
     $extDir = $extRoot . 'templates';
-    if (is_array($template->template_dir)) {
-      array_unshift($template->template_dir, $extDir);
-    }
-    else {
-      $template->template_dir = [$extDir, $template->template_dir];
-    }
+    $template->addTemplateDir($extDir);
 
     $currentUrl = CRM_Utils_System::currentPath() ?? '';
     if (stripos($currentUrl, 'civicrm/contact/search/custom') !== FALSE && CRM_Utils_Request::retrieve('ssID', 'Integer')