Bump NUnit from 3.14.0 to 4.0.0

Bumps [NUnit](https://github.com/nunit/nunit) from 3.14.0 to 4.0.0.
- [Release notes](https://github.com/nunit/nunit/releases)
- [Changelog](https://github.com/nunit/nunit/blob/master/CHANGES.md)
- [Commits](nunit/nunit@v3.14.0...v4.0.0)

---
updated-dependencies:
- dependency-name: NUnit
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

AssetRipper.TextureDecoder.Tests/AssetRipper.TextureDecoder.Tests.csproj

@@ -6,7 +6,7 @@
 
 	<ItemGroup>
 		<PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.8.0" />
-		<PackageReference Include="NUnit" Version="3.14.0" />
+		<PackageReference Include="NUnit" Version="4.0.0" />
 		<PackageReference Include="NUnit3TestAdapter" Version="4.5.0" />
 		<PackageReference Include="NUnit.Analyzers" Version="3.9.0">
 			<PrivateAssets>all</PrivateAssets>