Restrict pint test runs

### What is your issue?

Pint tests are failing on main — https://github.com/pydata/xarray/actions/runs/6817674274/job/18541677930

```
E               TypeError: no implementation found for 'numpy.min' on types that implement __array_function__: [<class 'pint.util.Quantity'>]
```

If we can't fix soon, should we disable?

CC @keewis 