Possibility to search for labels on pull requests for Github

[ePascalC]

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name: 🍭 Feature Request
about: Submit a new feature request

What feature is it?

Filter Github pull requests based on state and label (just like it exists already for the issues) into the RSS feed

What problem does this feature solve?

It is currently impossible to filter pull requests based on state and label. A new route would solve this.

Additional description

https://rsshub.app/github/issue/ABC/def/closed/XYZ will correctly show all closed issues with the label XYZ

Is there any possibility to create a route for the Pull requests too? So something like:
https://rsshub.app/github/pull/ABC/def/closed/XYZ

The route https://rsshub.app/github/pull/ABC/def already exists, but not the state and the label.

Thanks.

[github-actions]

👍 感谢提交该 Issue，请确保仔细阅读 Issue 模板，RSS 提案模板 或 Feature 提案模板 以便于测试。不符合模板将导致 Issue 被直接关闭。

👍 Thanks for the issue, please follow the Issue template, RSS proposal template or Feature proposal template. Otherwise the issue will be closed.

[ePascalC]

I adapted the original one.