chore(deps): update dependency xunit to v2.6.0

Directory.Packages.props

@@ -86,6 +86,6 @@
     <PackageVersion Include="Xunit.Priority" Version="1.1.6" />
     <PackageVersion Include="xunit.runner.visualstudio" Version="2.5.3" />
     <PackageVersion Include="Xunit.SkippableFact" Version="1.4.13" />
-    <PackageVersion Include="xunit" Version="2.5.3" />
+    <PackageVersion Include="xunit" Version="2.6.0" />
   </ItemGroup>
 </Project>