Bump xunit from 2.7.1 to 2.8.1 (#102)

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
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

Directory.Packages.props

@@ -13,7 +13,7 @@
     <PackageVersion Include="Microsoft.CodeAnalysis.CSharp.CodeFix.Testing" Version="1.1.1" />
     <PackageVersion Include="Microsoft.CodeAnalysis.CSharp.Analyzer.Testing" Version="1.1.1" />
     <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="17.9.0" />
-    <PackageVersion Include="xunit" Version="2.7.1" />
+    <PackageVersion Include="xunit" Version="2.8.1" />
     <PackageVersion Include="xunit.runner.visualstudio" Version="2.5.8" />
     <PackageVersion Include="FluentAssertions" Version="6.12.0" />
     <PackageVersion Include="coverlet.collector" Version="6.0.2" />