Fix psalm

Signed-off-by: Carl Schwan <carl@carlschwan.eu>

lib/Service/ActivityService.php

@@ -80,6 +80,7 @@ class ActivityService {
 	private ConfigService $configService;
 	private CurlService $curlService;
 	private MiscService $miscService;
+	private LoggerInterface $logger;
 
 	private ?array $failInstances = null;