feat!: Remove npm-use-webauthn header

[jumoel]

What

Remove the npm-use-webauthn header.

Why

The npm-auth-type header set in the npm-registry-fetch package will be used instead.

References

• Related https://github.com/github/npm/issues/5498
• Dependent on chore(main): release 13.2.0 npm-registry-fetch#124
• Related to feat: set 'npm-auth-type' header depending on config option npm-registry-fetch#123
• Resolves https://github.com/github/npm/issues/5577

[darcyclarke]

Is there any tests we can write for this &/or is this essentially captured downstream in the npm-registry-fetch implementation?

[jumoel]

@darcyclarke Your comment made me realise that we don't need this header after all, because we can use the header set in npm-registry-fetch instead.

I changed the PR to remove the header instead. It can be merged once the new release of npm-registry-fetch has landed.