(maint) Update dependency xunit to 2.9.3

Author: renovate[bot]

src/Diagramming.Tests/Diagramming.Tests.csproj

@@ -19,7 +19,7 @@
         <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.12.0" />
         <PackageReference Include="Moq" Version="4.20.72" />
         <PackageReference Include="Verify.Xunit" Version="28.7.0" />
-        <PackageReference Include="xunit" Version="2.9.2"/>
+        <PackageReference Include="xunit" Version="2.9.3"/>
         <PackageReference Include="xunit.analyzers" Version="1.18.0" />
         <PackageReference Include="xunit.runner.visualstudio" Version="3.0.0">
             <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>