chore(deps-dev): bump yoast/phpunit-polyfills from 3.0.0 to 4.0.0

Bumps [yoast/phpunit-polyfills](https://github.com/Yoast/PHPUnit-Polyfills) from 3.0.0 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@3.0.0...4.0.0)

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

Signed-off-by: dependabot[bot] <support@github.com>

composer.json

@@ -48,6 +48,6 @@
     "wp-coding-standards/wpcs": "^3.1",
     "dealerdirect/phpcodesniffer-composer-installer": "^1.0.0",
     "phpcompatibility/phpcompatibility-wp": "^2.1",
-    "yoast/phpunit-polyfills": "^3.0"
+    "yoast/phpunit-polyfills": "^4.0"
   }
 }