### Transform storage upgrades fixed

The Transform Secrets Engine storage upgrade introduced in 1.6.0 introduced
malformed configuration for transformations configured earlier than 1.6.0,
resulting in an error using these transformations if Vault is restarted
after the upgrade.  This issue exists on Vault 1.6.0 through 1.6.3, and is fixed
in Vault 1.6.4 and 1.7.0. Transformations configured on 1.6.0 or higher are 
unaffected.
