Bump NUnit.Runners from 2.6.4 to 3.9.0

Bumps [NUnit.Runners](https://github.com/nunit/nunit-console) from 2.6.4 to 3.9.0.
- [Release notes](https://github.com/nunit/nunit-console/releases)
- [Changelog](https://github.com/nunit/nunit-console/blob/master/CHANGES.txt)
- [Commits](https://github.com/nunit/nunit-console/commits/v3.9)

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

build/Uno.UI.Build.csproj

@@ -38,7 +38,7 @@
 			<Version>1.5.0.235</Version>
 		</PackageReference>
 		<PackageReference Include="NUnit.Runners">
-			<Version>2.6.4</Version>
+			<Version>3.9.0</Version>
 		</PackageReference>
 	</ItemGroup>