build(deps): bump the phonenumbers_test_minor_patch_updates group

Bumps the phonenumbers_test_minor_patch_updates group in /csharp/PhoneNumbers.Test with 1 update: [xunit](https://github.com/xunit/xunit).


Updates `xunit` from 2.6.4 to 2.6.6
- [Commits](xunit/xunit@2.6.4...2.6.6)

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

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

csharp/PhoneNumbers.Test/PhoneNumbers.Test.csproj

@@ -16,7 +16,7 @@
   <ItemGroup>
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.8.0" />
     <PackageReference Include="System.Text.RegularExpressions" Version="4.3.1" />
-    <PackageReference Include="xunit" Version="2.6.4" />
+    <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>