Regenerate package-lock.json

Fixes rescript-lang#388

Somehow a stale package-lock.json was incrementally generated during 8748fa0, without the needed `hasInstallScript` field.
CI still worked because CI was on an older npm which required regenerating the lockfile fresh.

Lessons:
- Be fast enough to generate something fresh please.
- Go was right. No lockfiles.

Author: chenglou