Wrong return type on create_timer()

[Rasmus-S-Kristensen]

🐛 Describe the bug
Type hint for return value of create_timer() is TaskBase, but that does not contain the cancel() function. Returning TimerTask seems more appropiate.

Current source:

azure-functions-durable-python/azure/durable_functions/models/DurableOrchestrationContext.py

Line 601 in 4ab004b

def create_timer(self, fire_at: datetime.datetime) -> TaskBase:

Example code:

    expiration = context.current_utc_datetime + timedelta(seconds=20)
    timeout_task = context.create_timer(expiration)
    timeout_task.cancel()  # <-- Pylance shows error: "Cannot access attribute "cancel" for class "TaskBase""

🤔 Expected behavior
You should be able to call cancel()without linter/type checker errors.

☕ Steps to reproduce
See above