Update yoast/phpunit-polyfills requirement from ^1.0 to ^2.0

Updates the requirements on [yoast/phpunit-polyfills](https://github.com/Yoast/PHPUnit-Polyfills) to permit the latest version.
- [Release notes](https://github.com/Yoast/PHPUnit-Polyfills/releases)
- [Changelog](https://github.com/Yoast/PHPUnit-Polyfills/blob/2.x/CHANGELOG.md)
- [Commits](Yoast/PHPUnit-Polyfills@1.0.0...2.0.0)

---
updated-dependencies:
- dependency-name: yoast/phpunit-polyfills
  dependency-type: direct:development
...

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

Author: dependabot[bot]

composer.json

@@ -33,7 +33,7 @@
     "dealerdirect/phpcodesniffer-composer-installer": "^0.7",
     "phpcompatibility/phpcompatibility-wp": "*",
     "sebastian/phpcpd": "^3.0 || ^4.0 || ^6.0",
-    "yoast/phpunit-polyfills": "^1.0"
+    "yoast/phpunit-polyfills": "^2.0"
   },
   "scripts": {
     "install-codestandards": [