Zendesk user sync not working for existing zendesk users when drupal email has capitals

I get a crash with or without the patch.

The new version of the Zendesk library throws an exception for this, so the code needs to be changed.

The exception message is:

API error from Zendesk:Client error: `POST https://d3v-joachim.zendesk.com/api/v2/users.json` resulted in a `422 Unprocessable Entity` response: {"error":"RecordInvalid","description":"Record validation errors","details":{"email":[{"description":"Email: capitals@he (truncated...) [details] {"error":"RecordInvalid","description":"Record validation errors","details":{"email":[@"description":"Email: capitals@here.com is already being used by another user","error":"DuplicateValue"]}}

I'm going to close this in favour of 🐛 zendesk_create_user() breaks when email address contains capital letters Needs work which proposed an approach which looks better.