Update docker/build-push-action action to v6

[renovate[bot]]

This PR contains the following updates:

Package	Type	Update	Change
docker/build-push-action	action	major	v5 -> v6

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Release Notes

docker/build-push-action (docker/build-push-action)

### [`v6`](https://togithub.com/docker/build-push-action/compare/v5...v6) [Compare Source](https://togithub.com/docker/build-push-action/compare/v5...v6)

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Configuration

📅 Schedule: Branch creation - At any time (no schedule defined), Automerge - At any time (no schedule defined).

🚦 Automerge: Disabled by config. Please merge this manually once you are satisfied.

♻ Rebasing: Never, or you tick the rebase/retry checkbox.

🔕 Ignore: Close this PR and you won't be reminded about this update again.

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• [ ] If you want to rebase/retry this PR, check this box

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