Update dependency clean-css-brunch to v3

[renovate[bot]]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
clean-css-brunch	~2.0.0 -> ~3.0.0

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Release Notes

brunch/clean-css-brunch (clean-css-brunch)

### [`v3.0.0`](https://togithub.com/brunch/clean-css-brunch/compare/2.10.0...3.0.0) [Compare Source](https://togithub.com/brunch/clean-css-brunch/compare/2.10.0...3.0.0) ### [`v2.10.0`](https://togithub.com/brunch/clean-css-brunch/compare/2.0.0...2.10.0) [Compare Source](https://togithub.com/brunch/clean-css-brunch/compare/2.0.0...2.10.0)

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Configuration

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🚦 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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