Fix docs build

[jbusecke]

Got errors in the doc build here, and here. I am not sure why this does not get resolved by conda. Testing this to see if that works as a quick fix.

• [ ] Closes #xxxx
• [ ] Tests added
• [ ] Passes pre-commit run --all-files
• [ ] User visible changes (including notable bug fixes) are documented in whats-new.rst
• [ ] New functions/methods are listed in api.rst