tskit 0.4 seems to be breaking tszip tests

[brianzhang01]

The tszip tests were passing on Nov 8, 2021. Then sometime between then and Jan 20, 2022, they began failing. Here's the latest CI runs, showing 46 failing tests.

https://app.circleci.com/pipelines/github/tskit-dev/tszip/102/workflows/085bcc06-8109-4b39-b907-4ab8047524ff/jobs/104

During that window, tskit 0.4 was released: https://pypi.org/project/tskit/#history.

I ran some things locally that seem to suggest that tszip 0.2.0 works fine with tskit 0.3.7, but not with tskit 0.4.0. Therefore, I'm pinpointing it on some changes in tskit 0.4. For now, I'll just stick to tskit 0.3.7 until this is resolved.

[molpopgen]

This is #54, I think.

[brianzhang01]

Yes you're right, sorry about that.

[molpopgen]

Yes you're right, sorry about that.

No worries.

[jeromekelleher]

Thanks for the report @brianzhang01 - yes this is a dupe of #54, so going to close.