Bump Xunit from 2.8.1 to 2.9.0 in /src

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
...

Signed-off-by: dependabot[bot] <support@github.com>

src/Directory.Packages.props

@@ -11,7 +11,7 @@
     <PackageVersion Include="NodaTime" Version="3.1.11" />
     <PackageVersion Include="ProjectDefaults" Version="1.0.128" />
     <PackageVersion Include="Verify.Xunit" Version="25.3.0" />
-    <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>