Fix PHPStan error: move optional parameter after required ones

PHP deprecates required parameters after optional ones. Move
the nullable WatchtowerClient parameter to the end of the
constructor.

Author: Sebbeben

src/Services/System/UpdateChecker.php

@@ -49,9 +49,9 @@ public function __construct(private readonly HttpClientInterface $httpClient,
         private readonly PrivacySettings $privacySettings, private readonly LoggerInterface $logger,
         private readonly InstallationTypeDetector $installationTypeDetector,
         private readonly GitVersionInfoProvider $gitVersionInfoProvider,
-        private readonly ?WatchtowerClient $watchtowerClient = null,
         #[Autowire(param: 'kernel.debug')] private readonly bool $is_dev_mode,
-        #[Autowire(param: 'kernel.project_dir')] private readonly string $project_dir)
+        #[Autowire(param: 'kernel.project_dir')] private readonly string $project_dir,
+        private readonly ?WatchtowerClient $watchtowerClient = null)
     {
 
     }