Add "Add assignee to PR" workflow

[masutaka]

Summary

Introduce the reusable workflow route06/actions/.github/workflows/add_assignee_to_pr.yml

Related Issue

Nothing

Changes

Create .github/workflows/add_assignee_to_pr.yml. This workflow was added to route06inc/template by route06inc/template#3

Testing

✅

Other Information

Nothing

[shige]

👍

[toyamarinyon]

I'd like to minimize the number of GitHub Actions that are run. What are the benefits of enforcing author assignment on pull requests?

Looking at OSS GitHub repositories, it's more common to see pull requests without assigned authors. For example:

• https://github.com/langchain-ai/langgraph/pulls?q=is:pr+is:close
• https://github.com/vercel/next.js/pulls?q=is:pr+is:close

Could you explain the reasoning behind this requirement?

[masutaka]

@toyamarinyon I just followed the convention of ROUTE06 and did not think too deeply about it.
If there is an advantage, it is that it may be used for data analysis in the future when the number of OSS repositories grows.

[masutaka]

@toyamarinyon @shige
I have no strong opinion on this PR. 👀
Toyama-san do not want to increase the number of GitHub Actions, and if there are no other requests, I will close this PR next week.

[shige]

@masutaka @toyamarinyon It doesn't matter whether I'm here or not, so let's close it now.