Bump xunit from 2.6.4 to 2.6.6 (#224)

Bumps [xunit](https://github.com/xunit/xunit) from 2.6.4 to 2.6.6.
- [Commits](xunit/xunit@2.6.4...2.6.6)

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

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

HelloOwinTests/HelloOwinTests.csproj

@@ -14,7 +14,7 @@
  <PackageReference Include="Microsoft.Owin.Diagnostics" Version="4.2.2" />
  <PackageReference Include="Microsoft.Owin.Testing" Version="4.2.2" />
  <PackageReference Include="MSFT.ParallelExtensionsExtras" Version="1.2.0" />
- <PackageReference Include="xunit" Version="2.6.4" />
+ <PackageReference Include="xunit" Version="2.6.6" />
  <PackageReference Include="xunit.runner.console" Version="2.6.6">
  <PrivateAssets>all</PrivateAssets>
  <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>