Add an error type for 406 errors

lib/liudesk_cmdb.rb

@@ -37,6 +37,8 @@ module LiudeskCMDB
         ForbiddenError.new body, code
       when "404"
         NotFoundError.new body, code
+      when "406"
+        NotAcceptableError.new body, code
       when "422"
         UnprocessableError.new body, code
       else
@@ -66,6 +68,7 @@ module LiudeskCMDB
 
   class ForbiddenError < RequestError; end
   class NotFoundError < RequestError; end
+  class NotAcceptableError < RequestError; end
   class UnprocessableError < RequestError; end
   class ServerError < RequestError; end