Issue-#3873

Replace deprecated functions with new syntax.

mod/proxy.php

@@ -2,6 +2,7 @@
 // Based upon "Privacy Image Cache" by Tobias Hößl <https://github.com/CatoTH/>
 
 use Friendica\App;
+use Friendica\Core\Config;
 use Friendica\Core\System;
 
 define('PROXY_DEFAULT_TIME', 86400); // 1 Day
@@ -258,7 +259,7 @@ function proxy_url($url, $writemode = false, $size = '') {
 		return $url;
 	}
 
-	if (get_config('system', 'proxy_disabled')) {
+	if (Config::get('system', 'proxy_disabled')) {
 		return $url;
 	}