feat: speed improvements

Signed-off-by: Sebastian Krupinski <root@LAPTOP-7DVOR6NC>

lib/Client/Protocol/Command/Argument/Search/Unseen.php

@@ -0,0 +1,13 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Gricob\IMAP\Protocol\Command\Argument\Search;
+
+final readonly class Unseen implements Criteria
+{
+    public function __toString(): string
+    {
+        return 'UNSEEN';
+    }
+}