Bump xunit from 2.6.6 to 2.9.0 (#149)

Bumps [xunit](https://github.com/xunit/xunit) from 2.6.6 to 2.9.0.
- [Commits](xunit/xunit@2.6.6...2.9.0)

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

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

Author: dependabot[bot]

tests/Directory.Packages.props

@@ -6,7 +6,7 @@
 
   <ItemGroup>
     <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="17.11.1" />
-    <PackageVersion Include="xunit" Version="2.6.6" />
+    <PackageVersion Include="xunit" Version="2.9.0" />
     <!-- Global Package References -->
     <GlobalPackageReference Include="coverlet.collector" Version="6.0.2" />
     <!-- Pinned dependency required to test out-of-support target frameworks -->