Bump xunit from 2.7.0 to 2.8.0

Bumps [xunit](https://github.com/xunit/xunit) from 2.7.0 to 2.8.0.
- [Commits](xunit/xunit@2.7.0...2.8.0)

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

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

Directory.Packages.props

@@ -12,7 +12,7 @@
 
     <!-- Test deps -->
     <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="17.10.0"/>
-    <PackageVersion Include="xunit" Version="2.7.0"/>
+    <PackageVersion Include="xunit" Version="2.8.0"/>
     <PackageVersion Include="xunit.runner.visualstudio" Version="2.5.7"/>
     <PackageVersion Include="Unquote" Version="6.1.0"/>
   </ItemGroup>