Update index.php

Require once on core files, to stop redeclare when composer has already done so.

index.php

@@ -8,6 +8,6 @@ define('PLUGINS_DIR', ROOT_DIR .'plugins/');
 define('THEMES_DIR', ROOT_DIR .'themes/');
 define('CACHE_DIR', LIB_DIR .'cache/');
 
-require(ROOT_DIR .'vendor/autoload.php');
-require(LIB_DIR .'pico.php');
+require_once(ROOT_DIR .'vendor/autoload.php');
+require_once(LIB_DIR .'pico.php');
 $pico = new Pico();