Debian bookworm's python3-venv seeds pip 23.0.1, which rejects the
PyTorch CPU index's typing_extensions wheel because its metadata spells
the name with an underscore. It then falls back to the sdist, whose build
needs flit_core, which that index does not carry.
Runs on pull_request_target so the workflow always comes from main, on the
confined runner tier. Installs CPU-only torch before the package so pip
does not pull the CUDA build, then runs pytest. .dejima/allowed-domains
declares the hosts the job fetches from.
branderson