Update python-attrs to 25.4.0, with the first work for Python 3.14 and PEP 749. There is a backwards-incompatible change in which class-level kw_only=True behavior is now consistent with dataclasses. See https://github.com/python-attrs/attrs/releases/tag/25.4.0 for much more detail.

Update python-cattrs to 25.3.0. There have been a couple of breaking changes – abstract sets are now structured into frozensets and sequences are structured into tuples – along with a number of other changes described in https://github.com/python-attrs/cattrs/blob/v25.3.0/HISTORY.md.