Can you support `merge_group` event in plan-preview-action ?

[TakumaKurosawa]

What would you like to be added:

I would like you to support the merge_group event in plan-preview-action.

Why is this needed:

My project is using merge queue.

Merge queue is failed with this error:

unexpected event merge_group, only "pull_request", "issue_comment" and "push" event are supported

Reference:

https://github.com/pipe-cd/pipecd/blob/7b471d7a9f2eb09ccbc0a9222b6e7adb08ea2edf/tool/actions-plan-preview/main.go#L231-L233

[github-actions[bot]]

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[niladrix719]

Hey, will try to raise a Pr for this

[t-kikuc]

@niladrix719 thank you for your interest, but please let us assign another developer. That's because good FIRST issues are intended for educating a new contributor. Please keep opportunities for other developers.

When new contributors got interested in this issue, please help them 👍

[t-kikuc]

@niladrix719 Of course, just investigating and providing hints of development here is welcome! Please let someone create a PR.