fix(security): Update expiration date in security.txt

Signed-off-by: Joas Schilling <coding@schilljs.com>

apps/settings/lib/WellKnown/SecurityTxtHandler.php

@@ -38,7 +38,7 @@ class SecurityTxtHandler implements IHandler {
 		}
 
 		$response = "Contact: https://hackerone.com/nextcloud
-Expires: 2024-04-30T23:00:00.000Z
+Expires: 2024-08-31T23:00:00.000Z
 Acknowledgments: https://hackerone.com/nextcloud/thanks
 Acknowledgments: https://github.com/nextcloud/security-advisories/security/advisories
 Policy: https://hackerone.com/nextcloud