Cannot open pango-cmip6 datastore with version 2025.7.9

### Description

I'm trying to open the esm catalog for pange-cmip6 with the code from the docstring for the function `intake.open_esm_datastore`. This is failing with the most recent version of intake-esm 2025.7.9. If I install intake-esm 2025.2.3 the code works.

I'm running this on MacOs 14.5 with python 3.13.5. which throws an OSError. I am able to run the example from the readme with on this system.

I've also tried running this on Ubuntu 2022.04.5 with python 3.13., but get a core dump, including when I try to import intake_esm to run show_versions. These issues also are not present with 2025.2.3

### What I Did

```
import intake
url = 'https://storage.googleapis.com/cmip6/pangeo-cmip6.json'
cat = intake.open_esm_datastore(url)
```

### Version information: output of `intake_esm.show_versions()`

For MacOs:
```
INSTALLED VERSIONS
------------------

cftime: 1.6.4
dask: 2025.7.0
fastprogress: 1.0.3
fsspec: 2025.7.0
gcsfs: None
intake: 2.0.8
intake_esm: 2025.7.9
netCDF4: 1.7.2
pandas: 2.3.1
requests: 2.32.4
s3fs: None
xarray: 2025.7.1
zarr: 3.1.0
```