It looks like pyyaml==6.0.0 has a faulty source distribution that we can't build (pip install pyyaml==6.0.0 --no-cache --force-reinstall --no-binary pyyaml fails). But pyyaml==6.0.1 works as expected. The documentation seems to build in a musl container, so it has to build from source.
Summary
It looks like
pyyaml==6.0.0has a faulty source distribution that we can't build (pip install pyyaml==6.0.0 --no-cache --force-reinstall --no-binary pyyamlfails). Butpyyaml==6.0.1works as expected. The documentation seems to build in a musl container, so it has to build from source.