module: fix Windows folder exports deprecation warning
This fixes an issue with the deprecation warning introduced in https://github.com/nodejs/node/pull/35747 which was triggering incorrectly for third-party package resolutions in Windows.
Should have tested the negative case fully, but at least it has made people aware of the deprecation who have been using Node.js 15.
An alternative might be to just go ahead and apply this warning for all resolutions anyway, but let's stick to the plan of a slow deprecation for now at least.
@nodejs/modules