Fix sessions.expires not being installed

src/pages/install.php

@@ -261,6 +261,7 @@ switch ($step) {
                 `id`      INT         NOT NULL PRIMARY KEY AUTO_INCREMENT,
                 `user`    INT         NOT NULL,
                 `session` VARCHAR(32) NOT NULL,
+                `expires` TIMESTAMP   NOT NULL DEFAULT CURRENT_TIMESTAMP(),
 
                 INDEX `idx_user` (`session`),
                 CONSTRAINT `FK_sessions_users` FOREIGN KEY (`user`) REFERENCES `users` (`id`) ON DELETE CASCADE