Update for xarray 2024.10.0

[khaeru]

Nightly tests began to fail with the release of xarray 2024.10.0, e.g. here

The failing tests are:

genno/tests/core/test_quantity.py::TestQuantity::test_sel_xarray[sparsedataarray] - TypeError: Vectorized indexing is not supported
genno/tests/test_operator.py::test_select1[sparsedataarray] - TypeError: Vectorized indexing is not supported

both via:

genno/core/sparsedataarray.py:274: in sel
    .sel(indexers=indexers, method=method, tolerance=tolerance, drop=drop)

This appears to be pydata/xarray#9694.

For mitigation:

• SparseDataArray is not the default genno.Quantity class currently. If using AttrSeries (the default), genno remains usable.
• If using SparseDataArray, use xarray < 2024.10.0.

To resolve:

• Track resolution of the upstream issue.
• Make any adjustments necessary in genno itself.