Update OAuthHttpClient.php

Fix PHP 8.4 deprecation: Implicitly marking parameter as nullable is deprecated, the explicit nullable type must be used instead

Author: sveldhuisen

src/OAuthHttpClient.php

@@ -84,7 +84,7 @@ public function request(string $method, string $url, array $options = []): Respo
         throw new RuntimeException();
     }
 
-    public function stream($responses, float $timeout = null): ResponseStreamInterface
+    public function stream($responses, ?float $timeout = null): ResponseStreamInterface
     {
         return $this->client->stream($responses, $timeout);
     }