Added xdebug extension to tests.yml.

Author: hexydec

.github/workflows/tests.yml

@@ -13,7 +13,7 @@ jobs:
         uses: php-actions/phpunit@v2
         with:
           php_version: 7.4
-          php_extensions: mbstring
+          php_extensions: mbstring xdebug
           bootstrap: src/autoload.php
           args: --coverage-text --coverage-clover=coverage.xml tests
           env: