Update copyright date to 2024

[Achiel]

Summary

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]

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All committers have signed the CLA.

[CLAassistant]

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[team-gateway-bot]

Cherry-pick failed for master, because it was unable to cherry-pick the commit(s).

Please cherry-pick the changes locally.

git remote add upstream https://github.com/kong/kong-ee
git fetch upstream master
git worktree add -d .worktree/cherry-pick-12393-to-master-to-upstream upstream/master
cd .worktree/cherry-pick-12393-to-master-to-upstream
git checkout -b cherry-pick-12393-to-master-to-upstream
ancref=$(git merge-base 51bd4cd91a03833b6c12628414e5ee22069d814f 47fd0dda4e5f1de20b4e7098611ece7985bb4498)
git cherry-pick -x $ancref..47fd0dda4e5f1de20b4e7098611ece7985bb4498

[team-gateway-bot]

Successfully created backport PR for release/3.6.x:

• #12460

[team-gateway-bot]

Cherry-pick failed for master, because it was unable to cherry-pick the commit(s).

Please cherry-pick the changes locally.

git remote add upstream https://github.com/kong/kong-ee
git fetch upstream master
git worktree add -d .worktree/cherry-pick-12393-to-master-to-upstream upstream/master
cd .worktree/cherry-pick-12393-to-master-to-upstream
git checkout -b cherry-pick-12393-to-master-to-upstream
ancref=$(git merge-base 51bd4cd91a03833b6c12628414e5ee22069d814f 47fd0dda4e5f1de20b4e7098611ece7985bb4498)
git cherry-pick -x $ancref..47fd0dda4e5f1de20b4e7098611ece7985bb4498