Bump xunit from 2.3.1 to 2.4.0

Bumps [xunit](https://github.com/xunit/xunit) from 2.3.1 to 2.4.0.
- [Release notes](https://github.com/xunit/xunit/releases)
- [Commits](https://github.com/xunit/xunit/commits)

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

OhmGraphite.Test/OhmGraphite.Test.csproj

@@ -6,7 +6,7 @@
 
   <ItemGroup>
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="15.8.0" />
-    <PackageReference Include="xunit" Version="2.3.1" />
+    <PackageReference Include="xunit" Version="2.4.0" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.3.1" />
     <DotNetCliToolReference Include="dotnet-xunit" Version="2.3.1" />
   </ItemGroup>