修正session前缀

src/Captcha.php

@@ -108,18 +108,18 @@ class Captcha
     {
         $key = $this->authcode($this->seKey) . $id;
         // 验证码不能为空
-        $secode = Session::get($key);
+        $secode = Session::get($key, '');
         if (empty($code) || empty($secode)) {
             return false;
         }
         // session 过期
         if (time() - $secode['verify_time'] > $this->expire) {
-            Session::delete($key);
+            Session::delete($key, '');
             return false;
         }
 
         if ($this->authcode(strtoupper($code)) == $secode['verify_code']) {
-            $this->reset && Session::delete($key);
+            $this->reset && Session::delete($key, '');
             return true;
         }
 
@@ -198,8 +198,8 @@ class Captcha
         $secode                = [];
         $secode['verify_code'] = $code; // 把校验码保存到session
         $secode['verify_time'] = time(); // 验证码创建时间
-        Session::set($key . $id, $secode);
-        
+        Session::set($key . $id, $secode, '');
+
         ob_start();
         // 输出图像
         imagepng($this->_image);