wipfix: correct contatenation of options

lib/Proxy/AbstractProxy.php

@@ -49,11 +49,11 @@ abstract class AbstractProxy
      */
     public function __construct(Configuration $conf, string $link)
     {
-        if (!filter_var($link, FILTER_VALIDATE_URL, FILTER_FLAG_PATH_REQUIRED & FILTER_FLAG_QUERY_REQUIRED)) {
+        if (!filter_var($link, FILTER_VALIDATE_URL, FILTER_FLAG_PATH_REQUIRED | FILTER_FLAG_QUERY_REQUIRED)) {
             $this->_error = 'Invalid URL given.';
             return;
         }
-        
+
         if (!str_starts_with($link, $conf->getKey('basepath') . '?') ||
             parse_url($link, PHP_URL_HOST) != parse_url($conf->getKey('basepath'), PHP_URL_HOST)
            ) {