Bump xunit from 2.4.1 to 2.9.3 (#2229)

---
updated-dependencies:
- dependency-name: xunit
  dependency-version: 2.9.3
  dependency-type: direct:production
  update-type: version-update:semver-minor
- dependency-name: xunit
  dependency-version: 2.9.3
  dependency-type: direct:production
  update-type: version-update:semver-minor
- dependency-name: xunit
  dependency-version: 2.9.3
  dependency-type: direct:production
  update-type: version-update:semver-minor
- dependency-name: xunit
  dependency-version: 2.9.3
  dependency-type: direct:production
  update-type: version-update:semver-minor
- dependency-name: xunit
  dependency-version: 2.9.3
  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]

Ix.NET/Source/System.Interactive.Async.Providers.Tests/System.Interactive.Async.Providers.Tests.csproj

@@ -23,7 +23,7 @@
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
     </PackageReference>
     <PackageReference Include="FluentAssertions" Version="6.4.0" />
-    <PackageReference Include="xunit" Version="2.4.1" />
+    <PackageReference Include="xunit" Version="2.9.3" />
   </ItemGroup>
 
   <ItemGroup>