Update dependency xunit to v2.6.6

[renovate[bot]]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
xunit	2.6.5 -> 2.6.6

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Release Notes

xunit/xunit (xunit)

### [`v2.6.6`](https://togithub.com/xunit/xunit/compare/2.6.5...2.6.6) [Compare Source](https://togithub.com/xunit/xunit/compare/2.6.5...2.6.6)

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Configuration

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