fix(actions): edit the pattern in changelog requirement checker

[liverpool8056]

Summary

Currently the CI checker doesn't throw any errors when there are items put just under kong/unreleased/. However, in this case, these changelog items cannot be recognized when generating changelog entries, therefore in this PR, edit the location pattern in changelog requirement which is intended to fix such a bug by eliminating items which are mistakenly put under kong/unreleased/ so that CI checker is able to shout out.

Checklist

• [ ] The Pull Request has tests
• [ ] A changelog file has been created under changelog/unreleased/kong or skip-changelog label added on PR if changelog is unnecessary. README.md
• [ ] There is a user-facing docs PR against https://github.com/Kong/docs.konghq.com - PUT DOCS PR HERE

Issue reference

Fix #[issue number]