ed25519 upstream has new commits

It seems https://github.com/pyca/ed25519.git has changed: Expected [main](https://github.com/pyca/ed25519/commits/main) to be commit aab70bc, found ce16bf5 instead ([diff](https://github.com/pyca/ed25519/compare/aab70bc53cae6a9f67dd1aab8552810d7a4ae382...main)). Please review changes, update the vendored copy if needed, and then update the expected hash in _vendor/test-ed25519-upstream.sh