Renovate[bot]: Update dependency terser to v5.19.4

[renovate[bot]]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
terser (source)	5.19.3 -> 5.19.4

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Pre-merge checks

• [x] Make sure the GitHub Actions tests are passing.

• [x] Run bin/compare-build-branch.sh locally on this branch and confirm that this PR is not causing unexpected changes to the build. Requirements to run this script: grunt build and nvm.

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Release Notes

terser/terser (terser)

### [`v5.19.4`](https://togithub.com/terser/terser/blob/HEAD/CHANGELOG.md#v5194) [Compare Source](https://togithub.com/terser/terser/compare/v5.19.3...v5.19.4) - Prevent creating very deeply nested ternaries from a long list of `if..return` - Prevent inlining classes into other functions, to avoid constructors being compared.

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Configuration

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♻ Rebasing: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.

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

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This PR has been generated by Mend Renovate. View repository job log here.

[mattyrob]

Local run of bin/compare-build-branch.sh renovate/terser-5.x returned:

Diff results for branch: renovate/terser-5.x
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       0 build-compare.diff

Noted changes in built WordPress packages we use so will commit those changes before merge, this is likely due to updates to packages, autoprefixer and terser conflicting.