chore(deps): update dependency pyyaml to v6.0.1
PyYAML fails to build using newer cython versions, the patch release doesn't change any code and only pins the cython dependency to a lower version.
Relevant:
https://github.com/yaml/pyyaml/issues/601
https://github.com/yaml/pyyaml/pull/702
https://github.com/cython/cython/issues/4568