Detect http protocol in providers.php

ocs/providers.php

@@ -23,7 +23,7 @@
 
 require_once '../lib/base.php';
 
-$url='http://'.substr(OCP\Util::getServerHost().$_SERVER['REQUEST_URI'], 0, -17).'ocs/v1.php/';
+$url=OCP\Util::getServerProtocol().'://'.substr(OCP\Util::getServerHost().$_SERVER['REQUEST_URI'], 0, -17).'ocs/v1.php/';
 
 echo('
 <providers>