update .NET Framework xunit refs

Author: MV10

test/Serilog.Sinks.MSSqlServer.Tests/Serilog.Sinks.MSSqlServer.Tests.csproj

@@ -42,8 +42,8 @@
   <ItemGroup Condition=" '$(TargetFramework)' == 'net452' ">
     <Reference Include="System" />
     <Reference Include="Microsoft.CSharp" />
-    <PackageReference Include="xunit" Version="2.2.0" />
-    <PackageReference Include="xunit.runner.visualstudio" Version="2.2.0" NoWarn="NU1701" />
+    <PackageReference Include="xunit" Version="2.3.0" />
+    <PackageReference Include="xunit.runner.visualstudio" Version="2.3.0" NoWarn="NU1701" />
     <Compile Include="Configuration\NetFramework.ConfigurationManager\**\*.cs" />
   </ItemGroup>