Kwargs after ParamSpec.args should be tolerated

[kdkavanagh]

Bug Report
I believe mypy's handling of ParamSpecs is slightly too restrictive. Currently, it validates that there are no args or kwargs after a ParamSpec.args argument other than **kwargs. I believe it's tolerable to have kwargs follow a ParamSpec.args

Related to #18278

To Reproduce

def f5(f: Callable[P, int], *args: P.args, extra_regular_arg: int, **kwargs: P.kwargs) -> int: ...  # E: Arguments not allowed after ParamSpec.args

def f6(f: Callable[P, int], *args: P.args, extra_kwarg: int = 123, **kwargs: P.kwargs) -> int: ...  # E: Arguments not allowed after ParamSpec.args

Expected Behavior
The first function above should continue to fail, while the second function should not throw an error

[brianschubert]

Thanks for the issue! However, the behavior you suggest is not permitted by the typing spec, which states:

Placing keyword-only parameters between the *args and **kwargs is forbidden.

Both extra_regular_arg in f5 and extra_kwarg in f6 are keyword-only parameters, so mypy is correct to reject them. The reason for this restriction explained in the Rejected Alternatives section of the original PEP: https://peps.python.org/pep-0612/#concatenating-keyword-parameters