Summary
Maintaining changelogs in a single markdown file in the repo is one of the easy ways to maintain and also keep consistency. Since Kong has multiple release versions, sometimes a bug fix needs to be backported to all the supported versions after it gets merged to the master branch. The backport bot is currently broken because of the git conflict.

We're Introducing a new way to maintain Kong's changelog, which makes the changelog item become an individual file. The idea is, that you don't get the conflict if you don't edit the same file.

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Co-authored-by: Hans Hübner <hans.huebner@gmail.com>
Co-authored-by: Wangchong Zhou <wangchong@konghq.com>
(cherry picked from commit 17c971b)

…1733)

The test suite build&test should ignore lowercase changelog directory.

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Co-authored-by: Wangchong Zhou <wangchong@konghq.com>