Avoid using internal function

Author: fdreamsu

src/session.php

@@ -35,9 +35,9 @@ private static function generateSid(int $agent): string {
         $tmp_string = base_convert($agent + 10, 10, 36);
         $tmp_string .= substr(base_convert($time, 10, 36), 1);
         $tmp_string .= substr(base_convert(crc32(SysContext::get('request_id')), 10, 36), 1);
-        $sid = strtolower($tmp_string . XString\GenerateRandomString(32 - 5 - strlen($tmp_string)));
+        $sid = strtolower($tmp_string . XString\GenerateRandomString(32 - 6 - strlen($tmp_string)));
         $crc = substr(base_convert(crc32($sid), 10, 36), 1);
-        $crc = str_repeat('0', 5 - strlen($crc)) . $crc;
+        $crc = str_repeat('0', 6 - strlen($crc)) . $crc;
         return $sid . $crc;
     }
     public static function getAgentMap(): Swango\HttpServer\Session\AgentMapInterface {
@@ -472,4 +472,4 @@ public function __call(string $name, $arguments) {
         cache::select(1);
         return $ret;
     }
-}
+}