chore(deps): update dependency xunit to 2.9.3

Author: renovate[bot]

src/ReactiveMvvm.Tests/ReactiveMvvm.Tests.csproj

@@ -14,7 +14,7 @@
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.10.0" />
     <PackageReference Include="NSubstitute" Version="5.1.0" />
     <PackageReference Include="ReactiveUI.Testing" Version="20.2.45" />
-    <PackageReference Include="xunit" Version="2.9.0" />
+    <PackageReference Include="xunit" Version="2.9.3" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.8.2">
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers</IncludeAssets>