Add unit test to make sure schema is up to date.

[joanise]

Could do it the same way as EveryVoiceTTS/EveryVoice#389

[dhdaines]

I don't have access to EveryVoice so I'll leave this to you or @roedoejet :)

[joanise]

We've been on the edge of making it public for a while now. Looking forward to that being done!