Bump xunit from 2.7.1 to 2.8.1

Bumps [xunit](https://github.com/xunit/xunit) from 2.7.1 to 2.8.1.
- [Commits](xunit/xunit@2.7.1...2.8.1)

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

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

src/Directory.Build.props

@@ -21,7 +21,7 @@
     <PropertyGroup>
         <LibraryFramework>netstandard2.0</LibraryFramework>
         <TestsNetCoreFramework>net6.0</TestsNetCoreFramework>
-        <XunitVersion>2.7.1</XunitVersion>
+        <XunitVersion>2.8.1</XunitVersion>
         <TestSdkVersion>17.10.0</TestSdkVersion>
         <CoverletVersion>6.0.2</CoverletVersion>
 	    <XunitRunneVisualstudio>2.5.8</XunitRunneVisualstudio>