[Bug] Infrequent polling test not properly skipped during time skipping

### Describe the bug

#152 added `test_infrequent_polling_workflow`, but put

```python
    if not env.supports_time_skipping:
        pytest.skip("Too slow to test with time-skipping disabled")
```

when likely meant

```python
    if env.supports_time_skipping:
        pytest.skip("Too slow to test with time-skipping disabled")
```