fix(symfony): allow null $data in PlaceholderAction (#8359)

Closes #8354

Author: soyuka

src/Symfony/EventListener/DeserializeListener.php

@@ -76,6 +76,10 @@ public function onKernelRequest(RequestEvent $event): void
         }
 
         if (!$operation->canDeserialize()) {
+            if (!$request->attributes->has('data')) {
+                $request->attributes->set('data', null);
+            }
+
             return;
         }
 

tests/Functional/JsonLd/InputOutputDtoTest.php

@@ -158,10 +158,6 @@ public function testInputOutputCycle(): void
 
     public function testCreateNoInputResource(): void
     {
-        if ($_SERVER['USE_SYMFONY_LISTENERS'] ?? false) {
-            $this->markTestSkipped('PlaceholderAction cannot resolve $data when input:false in event-listener mode.');
-        }
-
         $response = self::createClient()->request('POST', '/jsonld_no_inputs', [
             'headers' => ['Accept' => 'application/ld+json'],
         ]);