Run bump-pydantic and perform the fixes that let the unit tests run (and fail).

This clears the Pydantic warnings - many tests still error out.

It's missing because we exclude the 'overlays.rst' doc from craft-parts,
preferring instead our own.

It's not only no longer needed but newer versions use ruamel YAML, which is
currently not compatible with our yaml-dumping-needs: the fields are always
sorted by default, we would need to write a new string representer, etc.

This comes from the fix in part validation in craft-application

This gives us the config dict for free and keeps the models consistent.

There is a redirect from the previous one to this one but it breaks the
link checker.