fix: check mailbox capabilities

Author: Sn0wCrack

src/Folder.php

@@ -160,6 +160,10 @@ public function select(bool $force = false): void
      */
     public function quota(): array
     {
+        if (! in_array('QUOTA', $this->mailbox->capabilities())) {
+            throw new ImapCapabilityException('Unable to fetch mailbox quotas. IMAP server does not support QUOTA capability.');
+        }
+
         $responses = $this->mailbox->connection()->quotaRoot($this->path);
 
         $values = [];