Add unique assert to confirmation code for mobile numbers

src/Entity/MobileNumber.php

@@ -9,6 +9,8 @@ use Symfony\Component\Validator\Constraints as Assert;
 /**
  * @ORM\Entity
  * @ORM\Table(name="mobile_number")
+ * @UniqueEntity("id")
+ * @UniqueEntity("confirm_code")
  */
 class MobileNumber
 {