Dependency on `webidl-conversions@3` triggers esbuild warning

[yamadapc]

webidl-conversions version 3.0.1 has code which compares a number with -0 and triggers a warning when loaded on esbuild.

https://github.com/jsdom/webidl-conversions/blob/v3.0.1/lib/index.js#L67-L69

This is required by test-runner due to dependencies on node-fetch@2