fix: use regexp to handle follow up pr target

[tk3fftk]

Context

• trim trailing whitespace in follow-up comments #1660 is improved the problem but still there like adding lines before comment or update the comment line.

Objective

• Use regexp to handle follow up pr target for robustness
  • I think using PR label or something is robuster than using PR body string but I don't know well about tfaction

Check List

• Read CONTRIBUTING.md
  • Read OSS Contribution Guide
• Write a GitHub Issue before creating a Pull Request
  • Link to the issue: Extra whitespace detected at the end of targets in list-target job #1661
• All commits are signed
  • This repository enables Require signed commits, so all commits must be signed
• Avoid force push
• Do only one thing in one Pull Request

[suzuki-shunsuke]

Thank you for your contribution!

[github-actions]

🚀 Pull Request Branch was created or updated

Build link

The pull request branch pr/1665 was created or updated.

You can try this pull request in your workflows by changing tfaction version to pr/1665.

e.g.

- uses: suzuki-shunsuke/tfaction/setup@pr/1665

To update the pull request branch again, please run the workflow.

[suzuki-shunsuke]

v1.5.1 is out 🎉
https://github.com/suzuki-shunsuke/tfaction/releases/tag/v1.5.1