Deprecation in yaml conversion

[smmaurer]

In Pandas 1.2+, pandas.Index.to_native_types() is deprecated, raising warnings like the following:

This comes up in code that serializes data to yaml for storage and later reloading.

urbansim/utils/yamlio.py#L48

The replacement suggested in the message doesn't sound as general-purpose, but maybe it would work if Pandas is able to convert string representations of ints and floats back to the appropriate data type. Another option could be to use to_json().

pandas.Index.to_native_types()
pandas.Series.astype()
pandas.Series.to_json()

[mbarison]

I can confirm this is definitively broken with Pandas 2.0.0. The workaround is to replace pandas.Index.to_native_types() with pandas.Index.format()