fix test workflow

Author: jakubmikita

.github/workflows/test.yml

@@ -39,5 +39,6 @@ jobs:
         coverage: none
     - name: PHPUnit
       run: |
-        bin/install-wp-tests.sh wordpress_test root root 127.0.0.1:${{ job.services.mysql.ports['3306'] }} latest true
-        vendor/bin/phpunit
+        chmod 777 bin/install-wp-tests.sh
+        bash bin/install-wp-tests.sh wordpress_test root root 127.0.0.1:${{ job.services.mysql.ports['3306'] }} latest true
+        composer phpunit