Deprecate creating a :class:`typing.NamedTuple` class using keyword
arguments to denote the fields (``NT = NamedTuple("NT", x=int, y=str)``).
This will be disallowed in Python 3.15.
Use the class-based syntax or the functional syntax instead.

Two methods of creating ``NamedTuple`` classes with 0 fields using the
functional syntax are also deprecated, and will be disallowed in Python 3.15:
``NT = NamedTuple("NT")`` and ``NT = NamedTuple("NT", None)``. To create a
``NamedTuple`` class with 0 fields, either use ``class NT(NamedTuple): pass`` or
``NT = NamedTuple("NT", [])``.