Bump NUnit from 3.11.0 to 3.12.0

Bumps [NUnit](https://github.com/nunit/nunit) from 3.11.0 to 3.12.0.
- [Release notes](https://github.com/nunit/nunit/releases)
- [Changelog](https://github.com/nunit/nunit/blob/master/CHANGES.md)
- [Commits](nunit/nunit@v3.11...v3.12)

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

test/Unosquare.Tubular.Tests/Unosquare.Tubular.Tests.csproj

@@ -15,7 +15,7 @@
       <IncludeAssets>runtime; build; native; contentfiles; analyzers</IncludeAssets>
     </PackageReference>
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.2.0" />
-    <PackageReference Include="NUnit" Version="3.11.0" />
+    <PackageReference Include="NUnit" Version="3.12.0" />
     <PackageReference Include="NUnit3TestAdapter" Version="3.13.0" />
   </ItemGroup>