Update yoast/phpunit-polyfills requirement from ^2.0 to ^3.0

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/3.x/CHANGELOG.md)
- [Commits](Yoast/PHPUnit-Polyfills@2.0.0...3.0.0)

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

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

Author: dependabot[bot]

composer.json

@@ -22,7 +22,7 @@
     "phpcompatibility/phpcompatibility-wp": "*",
     "squizlabs/php_codesniffer": "3.*",
     "wp-coding-standards/wpcs": "*",
-    "yoast/phpunit-polyfills": "^2.0",
+    "yoast/phpunit-polyfills": "^3.0",
     "dealerdirect/phpcodesniffer-composer-installer": "^1.0.0",
     "dms/phpunit-arraysubset-asserts": "^0.4.0"
   },