postchecks to verify release

[pi0]

Yesterday i had encountered two random issues with npm otp API and github API that partially broke release cycle of two unjs package.. I had been thinking it could be nice if changelogen has automated post-check hooks to automatically test release.

I am still not sure about best implementation but here are some ideas to have:

• Make sure the package exists and published to the desired registry (default registry.npmjs.com)
• Make sure git tag and commit is pushed to the origin upstream
• Make sure GitHub release is properly done
• Make sure the published package includes all expected files (similar to unbuild prechecks) by trying to download tarball
• Custom user post checks (could be unbuild integration too!)