Fix a problem with previous release
What's Changed
* Set python-version as string by Zeitsperre in https://github.com/xarray-contrib/cf-xarray/pull/479
New Contributors
* Zeitsperre made their first contribution in https://github.com/xarray-contrib/cf-xarray/pull/479
**Full Changelog**: https://github.com/xarray-contrib/cf-xarray/compare/v0.8.5...v0.8.6