Composer Dev(deps-dev): Bump yoast/phpunit-polyfills from 2.0.4 to 4.0.0

Bumps [yoast/phpunit-polyfills](https://github.com/Yoast/PHPUnit-Polyfills) from 2.0.4 to 4.0.0.
- [Release notes](https://github.com/Yoast/PHPUnit-Polyfills/releases)
- [Changelog](https://github.com/Yoast/PHPUnit-Polyfills/blob/4.x/CHANGELOG.md)
- [Commits](Yoast/PHPUnit-Polyfills@2.0.4...4.0.0)

---
updated-dependencies:
- dependency-name: yoast/phpunit-polyfills
  dependency-version: 4.0.0
  dependency-type: direct:development
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

composer.json

@@ -52,7 +52,7 @@
 	},
 	"require-dev": {
 		"wp-phpunit/wp-phpunit": "^6.6.2",
-		"yoast/phpunit-polyfills": "^2.0.2",
+		"yoast/phpunit-polyfills": "^4.0.0",
 		"newfold-labs/wp-php-standards": "^1.2.4",
 		"wp-cli/i18n-command": "^2.6.3"
 	},