Update dependency NUnit to v4

[renovate[bot]]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
NUnit (source)	3.14.0 -> 4.0.0

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Release Notes

nunit/nunit (NUnit)

### [`v4.0.0`](https://togithub.com/nunit/nunit/blob/HEAD/CHANGES.md#NUnit-400---November-26-2023) All changes, see [release notes](https://docs.nunit.org/articles/nunit/release-notes/framework.html#nunit-400)

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Configuration

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[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (269d1ad) 100.00% compared to head (5c0719c) 100.00%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #123 +/- ## ========================================= Coverage 100.00% 100.00% ========================================= Files 8 8 Lines 119 119 Branches 14 14 ========================================= Hits 119 119 ```

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