Bump xunit from 2.8.1 to 2.9.0

Bumps [xunit](https://github.com/xunit/xunit) from 2.8.1 to 2.9.0.
- [Commits](xunit/xunit@2.8.1...2.9.0)

---
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]

test/json-ld.net.tests/json-ld.net.tests.csproj

@@ -23,7 +23,7 @@
   <ItemGroup>
     <PackageReference Include="coverlet.msbuild" Version="6.0.2" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.10.0" />
-    <PackageReference Include="xunit" Version="2.8.1" />
+    <PackageReference Include="xunit" Version="2.9.0" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.8.2" />
     <DotNetCliToolReference Include="dotnet-xunit" Version="2.3.1" />
   </ItemGroup>