Update DefaultCaptcha.php

Author: mageprince

app/code/Magento/Captcha/Block/Captcha/DefaultCaptcha.php

@@ -13,7 +13,7 @@ class DefaultCaptcha extends \Magento\Framework\View\Element\Template
     /**
      * @var string
      */
-    protected $_template = 'default.phtml';
+    protected $_template = 'Magento_Captcha::default.phtml';
 
     /**
      * @var string