Nightly Hypothesis tests failed

[Workflow Run URL](https://github.com/pydata/xarray/actions/runs/16333274224)
<details><summary>Python 3.12 Test Summary</summary>

```
properties/test_encode_decode.py::test_iso8601_decode: AttributeError: 'CFTimeStrategyISO8601' object has no attribute 'validate_called'
```

</details>
