bugfix in UtilitiesClient.stream_upload

[daniel-gratz]

In UtilitiesClient.stream_upload, the domo stream upload part api expects part_id to be contiguous. It seems to tolerate some discontinuities, but when uploading a large dataset the api eventually returns an error that there are too many gaps in the uploaded part_ids. This commit fixes this by using i as the part_id (instead of start) which will be contiguous.

I have only tested this code change by running it in my code, where it fixed the issue. If there is other testing that needs to be done, let me know how I can do that.