feat: deprecation on Gitalk: use Basic Authentication instead of OAuth

[razertory]

根据 github-api 的(最新文档 )[https://developer.github.com/changes/2020-02-10-deprecating-auth-through-query-param]，gitalk 目前需要替换为 Basic Auth。目前用 OAuth 配置的 gitalk 已经陆陆续续收到了邮件

Hi @razertory,

On February 22nd, 2020 at 10:32 (UTC) your application (razertory's blog) used its `client_id` and `client_secret` (with the User-Agent Mozilla/5.0 AppleWebKit/537.36 (KHTML, like Gecko; compatible; Googlebot/2.1; +http://www.google.com/bot.html) Chrome/79.0.3945.120 Safari/537.36) as part of a set of query parameters to access an endpoint through the GitHub API:

https://api.github.com/repositories/189442197/issues

Please use Basic Authentication instead as using OAuth credentials in query parameters has been deprecated.

Depending on your API usage, we'll be sending you this email reminder on a monthly basis.

Visit https://developer.github.com/changes/2020-02-10-deprecating-auth-through-query-param for more information about suggested workarounds and removal dates.

Thanks,
The GitHub Team

目前已亲测用如下的改动可以修复这个问题。