Investigate Python 3.8 windows test failure

This was from unrelated code change:

```
_____________________________ test_interval_timer _____________________________

def test_interval_timer():
func = mock.Mock()
timer = IntervalTimer(function=func, interval=0.1, args=(1,), kwargs={"a": "b"})
timer.start()
time.sleep(0.25)
try:
> assert func.call_count == 2
E AssertionError: assert 1 == 2
E + where 1 = .call_count

tests\utils\threading_tests.py:46: AssertionError
```