chore(ci): build&test should ignore lowercase changelog directory

[windmgc]

Summary

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

Checklist

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

[team-gateway-bot]

The backport to release/3.4.x failed:

The process '/usr/bin/git' failed with exit code 1

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add .worktrees/backport-release/3.4.x release/3.4.x
# Navigate to the new working tree
cd .worktrees/backport-release/3.4.x
# Create a new branch
git switch --create backport-11733-to-release/3.4.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 34178832f9fcb3bd89d0b90d718c97abe8f05125
# Push it to GitHub
git push --set-upstream origin backport-11733-to-release/3.4.x
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-release/3.4.x

Then, create a pull request where the base branch is release/3.4.x and the compare/head branch is backport-11733-to-release/3.4.x.