Fix incorrect PHPUnit config file reference

Author: chrisdicarlo

.github/workflows/run-tests-L9.yml

@@ -47,4 +47,4 @@ jobs:
           composer require "laravel/framework:${{ matrix.laravel }}" "orchestra/testbench:${{ matrix.testbench }}" "symfony/console:>=4.3.4" "mockery/mockery:^1.3.2" --no-interaction --no-update
           composer update --${{ matrix.dependency-version }} --prefer-dist --no-interaction
       - name: Execute tests
-        run: vendor/bin/phpunit -c phpunit-laravel8.xml.dist
+        run: vendor/bin/phpunit -c phpunit-laravel9.xml.dist