fix response `content-type` is not set if access without access token

Kairlec

2023-05-15 ca103731c721aae3f5f622e58c679ed5c09fd9e9

 web_src/index.html

@@ -15,5 +15,6 @@
    <script type="text/javascript" src="./static/js/ZLMRTCClient.js"></script>
    <script type="text/javascript" src="./static/js/config.js"></script>
    <div id="app"></div>

  </body>
</html>