build(deps): bump xunit from 2.5.1 to 2.6.1 in /src (#345)

Bumps [xunit](https://github.com/xunit/xunit) from 2.5.1 to 2.6.1.
- [Commits](xunit/xunit@2.5.1...2.6.1)

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

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

src/Directory.build.props

@@ -33,7 +33,7 @@
 	<ItemGroup Condition="'$(IsTestProject)' == 'true'">
 		<PackageReference Include="ReactiveUI.Testing" Version="19.*" />
 		<PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.7.2" />
-		<PackageReference Include="xunit" Version="2.5.1" />
+		<PackageReference Include="xunit" Version="2.6.1" />
 		<PackageReference Include="xunit.runner.console" Version="2.6.1" />
 		<PackageReference Include="xunit.runner.visualstudio" Version="2.5.1" />
 		<PackageReference Include="Xunit.StaFact" Version="1.1.11" />