mismatch between docs and type returned for timer tasks

🐛 **Describe the bug**
per #322, the type hinting was not updated to match a type that has the `is-cancelled` property and `cancel()` method. The patch otherwise works beautifully.

🤔 **Expected behavior**
Just some intellisense, no functional issues

Thanks for the work on this repo!

The issue names no files or tests. Start by reviewing the type-hinting change in #322 and locating the timer-task return type; confirm it exposes is-cancelled and cancel() for IntelliSense, then run the relevant existing tests if they are identified.

Written by the indexing model from the issue text.