timeout: Correct thread id type passed to PyThreadState_SetAsyncExc.
timeout: Correct thread id type passed to PyThreadState_SetAsyncExc.

This type changed in Python 3.7:
https://github.com/python/cpython/pull/781

Signed-off-by: Anders Kaseorg <dfdb7392591db597bc41cf266a9c3bc12a2706e5@zulip.com>

zulip/zulip,zulip/zulip,zulip/zulip,zulip/zulip,zulip/zulip,zulip/zulip,zulip/zulip