stubgen may generate (*args, *, ...)

I ran stubgen recursively on the asyncio package, and found this in the output:
```py
    def subprocess_exec(self, protocol_factory, program, *args, *, stdin: Any = ..., stdout: Any = ..., stderr: Any = ..., universal_newlines: bool = ..., shell: bool = ..., bufsize: int = ..., **kwargs): ...
```