Eli Rykoff can you take a look at this please?
It's mostly removal but there are also some test cleanups. I've moved the read_curated_calibs code over from pipe_tasks and retained the edit history but you can ignore the commits for those for anything older than the last week. Test code was added for ExposureIdInfo.
The obs packages include removal of 2to3 code. pipe_tasks loses the read_curated_calibs. I had to make some typing fixes to daf_butler for a type annotation in ExposureIdInfo.