Use PEP 570 syntax in stdlib (#11250)

stdlib/_posixsubprocess.pyi

@@ -6,27 +6,28 @@ from typing import SupportsIndex
 if sys.platform != "win32":
     def cloexec_pipe() -> tuple[int, int]: ...
     def fork_exec(
-        __args: Sequence[StrOrBytesPath] | None,
-        __executable_list: Sequence[bytes],
-        __close_fds: bool,
-        __pass_fds: tuple[int, ...],
-        __cwd: str,
-        __env: Sequence[bytes] | None,
-        __p2cread: int,
-        __p2cwrite: int,
-        __c2pread: int,
-        __c2pwrite: int,
-        __errread: int,
-        __errwrite: int,
-        __errpipe_read: int,
-        __errpipe_write: int,
-        __restore_signals: int,
-        __call_setsid: int,
-        __pgid_to_set: int,
-        __gid: SupportsIndex | None,
-        __extra_groups: list[int] | None,
-        __uid: SupportsIndex | None,
-        __child_umask: int,
-        __preexec_fn: Callable[[], None],
-        __allow_vfork: bool,
+        args: Sequence[StrOrBytesPath] | None,
+        executable_list: Sequence[bytes],
+        close_fds: bool,
+        pass_fds: tuple[int, ...],
+        cwd: str,
+        env: Sequence[bytes] | None,
+        p2cread: int,
+        p2cwrite: int,
+        c2pread: int,
+        c2pwrite: int,
+        errread: int,
+        errwrite: int,
+        errpipe_read: int,
+        errpipe_write: int,
+        restore_signals: int,
+        call_setsid: int,
+        pgid_to_set: int,
+        gid: SupportsIndex | None,
+        extra_groups: list[int] | None,
+        uid: SupportsIndex | None,
+        child_umask: int,
+        preexec_fn: Callable[[], None],
+        allow_vfork: bool,
+        /,
     ) -> int: ...