Register the Symfony test listener explicitly

This makes sure deprecations are properly reported.

Author: stof

phpunit.xml.dist

@@ -13,4 +13,7 @@
             <directory suffix="Test.php">./tests</directory>
         </testsuite>
     </testsuites>
+    <listeners>
+        <listener class="Symfony\Bridge\PhpUnit\SymfonyTestsListener"/>
+    </listeners>
 </phpunit>