Bump xunit from 2.6.5 to 2.6.6

Bumps [xunit](https://github.com/xunit/xunit) from 2.6.5 to 2.6.6.
- [Commits](xunit/xunit@2.6.5...2.6.6)

---
updated-dependencies:
- dependency-name: xunit
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

examples/Xunit.Microsoft.DependencyInjection.ExampleTests/Xunit.Microsoft.DependencyInjection.ExampleTests.csproj

@@ -10,7 +10,7 @@
 
 	<ItemGroup>
 		<PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.8.0" />
-		<PackageReference Include="xunit" Version="2.6.5" />
+		<PackageReference Include="xunit" Version="2.6.6" />
 		<PackageReference Include="xunit.runner.visualstudio" Version="2.5.6">
 		  <PrivateAssets>all</PrivateAssets>
 		  <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>