Test for malformed POST/PUT when contact information is not a list
Test for malformed POST/PUT when contact information is not a list

 - just testing that the error that comes back vaguely makes sense,
   we don't want to be getting a 500 / crash [#134425439]

alphagov/digitalmarketplace-api,alphagov/digitalmarketplace-api,alphagov/digitalmarketplace-api