fix(deps): update dependency execa to v4

[renovate[bot]]

This PR contains the following updates:

Package	Type	Update	Change
execa	dependencies	major	3.4.0 -> 4.0.0

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Release Notes

sindresorhus/execa

### [`v4.0.0`](https://togithub.com/sindresorhus/execa/releases/v4.0.0) [Compare Source](https://togithub.com/sindresorhus/execa/compare/v3.4.0...v4.0.0) #### Breaking changes - Require Node.js 10 ([`5a9c76f`](https://togithub.com/sindresorhus/execa/commit/5a9c76f)) - Add `stderr` and `stdout` to [`error.message`](https://togithub.com/sindresorhus/execa#message). A new property [`error.shortMessage`](https://togithub.com/sindresorhus/execa#shortmessage) is now available to retrieve the error message without `stderr` nor `stdout` ([#​397](https://togithub.com/sindresorhus/execa/issues/397)) #### Bug fixes - Fix `childProcess.kill()` not working with Electron ([#​400](https://togithub.com/sindresorhus/execa/issues/400))

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