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>

Author: dependabot[bot]

dotnet-json.Tests/dotnet-json.Tests.csproj

@@ -13,7 +13,7 @@
   <ItemGroup>
     <PackageReference Include="FluentAssertions" Version="6.12.0" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.10.0" />
-    <PackageReference Include="xunit" Version="2.7.1" />
+    <PackageReference Include="xunit" Version="2.8.1" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.8.1" PrivateAssets="All" />
     <PackageReference Include="coverlet.collector" Version="6.0.2" PrivateAssets="All" />
   </ItemGroup>