fix(accounts): remove unique label key

This commit removes the unique label restriction from the account table
in the database.  Given that the approved chart of accounts from the
Ministry of Health has duplicate labels, we are removing this
restriction.

server/models/schema.sql

@@ -25,7 +25,6 @@ CREATE TABLE `account` (
   `is_charge` TINYINT(1) DEFAULT NULL,
   PRIMARY KEY (`id`),
   UNIQUE KEY `account_1` (`number`),
-  UNIQUE KEY `account_2` (`label`),
   KEY `type_id` (`type_id`),
   KEY `enterprise_id` (`enterprise_id`),
   KEY `cc_id` (`cc_id`),