Extra settings in Settings model are unintentionally forbidden?

[andkay]

Describe the bug
In testing the new recommended UV-based installation of the latest version of ActivitySim, CMAP's model crashes because latest does not allow "extra" settings in the core settings.yaml or settings_mp.yaml file. Their mainline model uses v1.2.1 and runs without error using the same settings, which makes sense as model validation was added in v1.3.0.

Forbidding extra settings is a completely valid way to configure a Pydantic model), but the code context around the traceback strongly suggests that a fatal exception is not the intended behavior.

If others agree, this should be a relatively quick fix.

Expected behavior
Expected to receive a DeprecationWarning along with a log of settings that will be ingnored rather than a fatal ValidationError

Screenshots

[andkay]

After @i-am-sijia mentioned the refactor from slice.except to slice.exclude, I do see what's causing the error.

While Settings allows extras, MultiProcessStepSlice is its own model which explicitly forbids extras. The nesting just obscures which model is complaining a little bit.

I think this can be closed, but still may want to revisit how extras are handled more generally for clarity.