Allow extending client

Author: joelwurtz

src/Client.php

@@ -33,6 +33,6 @@ public static function create($httpClient = null)
         $messageFactory = \Http\Discovery\MessageFactoryDiscovery::find();
         $serializer = new \Symfony\Component\Serializer\Serializer(\Docker\API\Normalizer\NormalizerFactory::create(), [new \Symfony\Component\Serializer\Encoder\JsonEncoder(new \Symfony\Component\Serializer\Encoder\JsonEncode(), new \Symfony\Component\Serializer\Encoder\JsonDecode())]);
 
-        return new self($httpClient, $messageFactory, $serializer);
+        return new static($httpClient, $messageFactory, $serializer);
     }
 }

src/ClientAsync.php

@@ -32,6 +32,6 @@ public static function create($httpClient = null)
         }
         $serializer = new \Symfony\Component\Serializer\Serializer(\Docker\API\Normalizer\NormalizerFactory::create(), [new \Symfony\Component\Serializer\Encoder\JsonEncoder(new \Symfony\Component\Serializer\Encoder\JsonEncode(), new \Symfony\Component\Serializer\Encoder\JsonDecode())]);
 
-        return new self($httpClient, $serializer);
+        return new static($httpClient, $serializer);
     }
 }