Bump xunit from 2.8.1 to 2.9.0 (#322)

Bumps xunit from 2.8.1 to 2.9.0.

---
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

@@ -16,7 +16,7 @@
     <PackageVersion Include="NonBlocking" Version="2.1.2" />
     <PackageVersion Include="NUnit" Version="4.1.0" />
     <PackageVersion Include="NUnit3TestAdapter" Version="4.5.0" />
-    <PackageVersion Include="xunit" Version="2.8.1" />
+    <PackageVersion Include="xunit" Version="2.9.0" />
     <PackageVersion Include="xunit.runner.visualstudio" Version="2.8.2" />
   </ItemGroup>
 </Project>