Follow #20987, update docs issue-pull-request-templates.zh-cn.md
<!--
Please check the following:
1. Make sure you are targeting the `main` branch, pull requests on
release branches are only allowed for bug fixes.
2. Read contributing guidelines:
https://github.com/go-gitea/gitea/blob/main/CONTRIBUTING.md
3. Describe what your pull request does and which issue you're targeting
(if any)
-->
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
