Remove deprecation linked to kernel shutdown

src/Bundle/ChillMainBundle/Tests/Controller/PermissionApiControllerTest.php

@@ -23,8 +23,15 @@ final class PermissionApiControllerTest extends WebTestCase
 {
     use PrepareClientTrait;
 
+    protected function tearDown(): void
+    {
+        self::ensureKernelShutdown();
+    }
+
     public function testDenormalizingObject()
     {
+        // for a unknown reason, the kernel may be booted before running this test...
+        self::ensureKernelShutdown();
         $client = $this->getClientAuthenticated();
 
         $client->request(