joriscode

Hi, Can you provide more context? The version `{{VERSION}}` in `setup.py` is replaced during the CI (see `bin/fill_placeholders`)

I bumped into the same issue. Searching for _AttributeError: cython_sources_ lead me to https://github.com/yaml/pyyaml/issues/601. When I locally downgraded `PyYaml` to `5.3.1`, the installation was successful. Ps: #222 appears to be...

#219 fixes the issue and it makes more sense than downgrading `PyYaml`