Add version 2.6

Author: natanfelles

src/server_config.php

@@ -19,7 +19,7 @@
 	   'max_execution_time'     => 360,
    ],
    'server'          => [
-	   'PHPSERVER_VERSION' => '2.5',
+	   'PHPSERVER_VERSION' => '2.6',
    ],
 ];