Catch and re-raise CancelledError

[alexrudd2]

See https://github.com/numat/controllers/issues/1596

@juli4nb4dillo
I prefer this approach to catching CancelledError in the controllers.
(1) The docs strongly advise against swallowing CancelledError
(2) We know that raising TimeoutError works without killing the controller.

[juli4nb4dillo]

It may work unless the CancelledError is raised on the await self.connectTask
Can we leave a trace of the error captured? In case we need to debug if it was a Cancel, Timeout or Connect error?

[alexrudd2]

@juli4nb4dillo This appears to be working well. (I just watched trim1 cycle through.)
However, Jan is talking about releasing pymodbus soon. He moves fast so my guess is this week.

There's a slight chance this is relevant: pymodbus-dev/pymodbus#1702

Anyways, let's keep this running a bit until the new release.

[alexrudd2]

Closing in favor of approaches discussed in https://github.com/numat/controllers/issues/1596