Update CI test environments

[GenevieveBuckley]

This PR:

• Updates the python 3.9 CI test environment, with a configuration I've checked works on arm64 Mac.
• Updates all of the environment yaml files to use dask==2024.4.1 (see Pin dask to 2024.4.1 to avoid error during dask.dataframe import with python 3.11.9 #363)

I didn't think we needed to do this, since all of the CI checks for #363 passed before we merged it, but manually triggering CI on the main branch is failing (see here). So this is an attempt to fix that problem.

[GenevieveBuckley]

We need to wait for the CI checks to finish running, and see if they all successfully create conda environments. Then we can commit this suggestion, and merge the PR.

Note: we are still expecting to see pytest failures here, which will be fixed by #366. But if pytest runs at all, then the conda environment definitely was created properly.