Update to platform specific dask schedulers example run scripts

[rickecon]

In the OG-Core package code and in the example run scripts, and subsequently in all the country calibration repositories example run scripts, we need to update the Dask scheduler calls to the platform-specific calls recommended in PR #1049.

Particularly

• For Windows users: scheduler="threads"
• For Mac and Linux users: scheduler=dask.multiprocessing.get

cc: @jdebacker

[jdebacker]

@rickecon Was reminded of this yesterday when grading some students problem sets. They had worked through the exercises in the UN-OG Training. When doing exercise 14.1, which is to run the OG-Core example script, students' run times were all greater than 7 hours. They were all on relatively new Windows computers.

This is with J=7 and takes less than 45 minutes on my machine (a Mac). I think it's very important we find the optimal setup for Windows.