chore: auto-close issues

[knqyf263]

Description

Issues created by non-maintainers are closed as Trivy uses GitHub Discussions for triaging bug fixes, feature requests, etc.

Related issues

• OCI Tarballs not working #5136
• README has broken link to "Scanning Coverage" page #5110
• Hang on recursive terraform module #5087
• Invalid purls due of a final slash #5085
• etc.

Checklist

• I've read the guidelines for contributing to this repository.
• I've followed the conventions in the PR title.
• I've added tests that prove my fix is effective or that my feature works.
• I've updated the documentation with the relevant information (if needed).
• I've added usage information (if the PR introduces new options)
• I've included a "before" and "after" example to the description (if the PR is a user interface change).

[masahiro331]

How about mentioning the reasons why issues are automatically closed in this document?
https://aquasecurity.github.io/trivy/v0.45/community/contribute/issue/