Update docker/setup-buildx-action action to v3

[renovate[bot]]

This PR contains the following updates:

Package	Type	Update	New value	References	Sourcegraph
docker/setup-buildx-action	action	major	v3	source

Test plan: CI should pass with updated dependencies. No review required: this is an automated dependency update PR.

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Release Notes

docker/setup-buildx-action (docker/setup-buildx-action)

### [`v3`](https://togithub.com/docker/setup-buildx-action/compare/v2...v3) [Compare Source](https://togithub.com/docker/setup-buildx-action/compare/v2...v3) ### [`v2`](https://togithub.com/docker/setup-buildx-action/compare/v1...v2) [Compare Source](https://togithub.com/docker/setup-buildx-action/compare/v1...v2)

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Configuration

📅 Schedule: Branch creation - "on the 1st through 7th day of the month" in timezone America/Los_Angeles, Automerge - At any time (no schedule defined).

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

♻ Rebasing: Whenever PR becomes conflicted, 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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