Update dependency @rails/webpacker to v4.3.0

[renovate[bot]]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
@rails/webpacker	4.2.2 -> 4.3.0

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Release Notes

rails/webpacker

### [`v4.3.0`](https://togithub.com/rails/webpacker/compare/v4.2.2...v4.3.0) [Compare Source](https://togithub.com/rails/webpacker/compare/v4.2.2...v4.3.0)

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Configuration

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