fix: update usage of commonmark library

www/selectsource.php

@@ -151,10 +151,10 @@ if (!empty($wayfConfig['footer']['format']) && $wayfConfig['footer']['format'] =
     foreach ($wayfConfig['footer']['sections'] as $key => $value) {
         if (is_array($value)) {
             foreach ($wayfConfig['footer']['sections'][$key] as $subKey => $subValue) {
-                $wayfConfig['footer']['sections'][$key][$subKey] = $converter->convertToHtml($subValue);
+                $wayfConfig['footer']['sections'][$key][$subKey] = $converter->convertToHtml($subValue)->getContent();
             }
         } else {
-            $wayfConfig['footer']['sections'][$key] = $converter->convertToHtml($value);
+            $wayfConfig['footer']['sections'][$key] = $converter->convertToHtml($value)->getContent();
         }
     }
 }