Make Updater.stop Independent of CancelledError

[Bibo-Joshi]

See #4125 for discussion

Since the tests for these things usually don't run well on Windows, I haven't run the unit tests yet - let's see.
Adding new unit tests will also likely be chellanging. If the test coverage doesn't drop, I might be content with leaving as is 😬

[Bibo-Joshi]

All right, tests seem to be stuck. will have to debug on linux

[Bibo-Joshi]

Test coverage seems to be fine and as expected adjusting the existing tests was already rather annoying, so tbh I'm not eager to try and add another unit test here.
I manually ran the customwebhook as well, which still works fine.

[harshil21]

code looks good. Didn't have a very close look at the tests.. they are kind of a black box because of so many Event's. I assume you ran an example bot on both Windows and linux and checked if Ctrl+C works well?

[Bibo-Joshi]

Didn't have a very close look at the tests.. they are kind of a black box because of so many Event's.

They are certainly not very pretty :/

I assume you ran an example bot on both Windows and linux and checked if Ctrl+C works well?

Yes, I ran echobot & the example from #4125.