Fix unexpected posts in recent posts list issue

[LukeHong]

Pull Request type

Please check the type of change your PR introduces:

• [x] Bug-fix
• [ ] Feature (functionality, design, translations, etc.)
• [ ] Documentation change
• [ ] Project management (tests, CI, GitHub configuration, etc.)
• [ ] Other (please describe):

Current state

Issue Number(s):

Closes #451

Proposed changes

The featured posts might appear in the "Recent Posts" list in the sidebar if those featured posts are older than the last post in the list.

Screenshots, if applicable

Checklist

• [x] Bug-fixes and new features: I have tested locally with the latest release of Hugo extended. This requirement is a standard.
• [x] Bug-fixes, new features, and doc changes: I have updated the relevant documentation as part of this PR.
• [x] All PRs: I have signed off (using git commit -s ...), or if not possible due to developer environment constraints, will comment below confirming that I am adhering to the Developer Certificate of Origin.

[chipzoller]

@onweru @rootwork: Do you agree here?