Fix bug with `Cargo.toml` not being generated for workspace alone
Fix bug with `Cargo.toml` not being generated for workspace alone

Signed-off-by: Martin Larralde <c01eaecb7b9646a7fd0f3d0d81c1411af7cf0521@ens-cachan.fr>

PyO3/setuptools-rust,PyO3/setuptools-rust