Specify use public npm registry

[karenyrx]

Description

Was using an iternal registry and got these errors when running the local protobuf convert guide:

npm error code E403
npm error 403 403 Forbidden - GET https://unpm.uberinternal.com/lodash/-/lodash-4.17.23.tgz
npm error 403 In most cases, you or one of your dependencies are requesting
npm error 403 a package version that is forbidden by your security policy, or
npm error 403 on a server you do not have access to.
npm error A complete log of this run can be found in: /home/user/.npm/_logs/2026-01-26T05_47_13_721Z-debug-0.log

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