Dependencies used inside `hook/` must be regular dependencies, not dev_dependencies

[goderbauer]

The validator complains that dependencies only used inside a build hook (which is placed inside the top-level hook directory) should be dev_dependnecies (because they are only used outside of lib/). That is not correct as also stated in the documentation for hooks:

You need to add the dependencies under dependencies, not dev_dependencies. The hooks will be run by packages and applications depending on your package, so the Dart code needs to be part of the resolution in those packages.

[robbecker-wf]

Thanks for reporting. It appears hooks is relatively new and still in preview. We'll look to add support for hooks properly but in the meantime as a workaround, you can configure an ignore https://pub.dev/packages/dependency_validator#configuration