test: skip unicode test on windows instead of lowering the Node version

[sapphi-red]

Description

The fix (nodejs/node#50650) for the Windows unicode fs bug (nodejs/node#48673) seems to be not included in the next LTS release (nodejs/node#50682).
This means we'll need to pin the version for at least 2 week more.

I think it's better to skip this (edge case) test rather than running in the older version.

Additional context

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What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

Before submitting the PR, please make sure you do the following

• Read the Contributing Guidelines, especially the Pull Request Guidelines.
• Check that there isn't already a PR that solves the problem the same way to avoid creating a duplicate.
• Provide a description in this PR that addresses what the PR is solving, or reference the issue that it solves (e.g. fixes #123).
• Update the corresponding documentation if needed.
• Ideally, include relevant tests that fail without this PR but pass with it.