Bump Verify.Xunit from 11.24.0 to 13.3.1 in /Rx.NET/Source

Bumps [Verify.Xunit](https://github.com/VerifyTests/Verify) from 11.24.0 to 13.3.1.
- [Release notes](https://github.com/VerifyTests/Verify/releases)
- [Commits](VerifyTests/Verify@11.24.0...13.3.1)

---
updated-dependencies:
- dependency-name: Verify.Xunit
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

Rx.NET/Source/tests/Tests.System.Reactive.ApiApprovals/Tests.System.Reactive.ApiApprovals.csproj

@@ -26,7 +26,7 @@
 
   <ItemGroup>
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.11.0" />
-    <PackageReference Include="Verify.Xunit" Version="11.24.0" />
+    <PackageReference Include="Verify.Xunit" Version="13.3.1" />
     <PackageReference Include="xunit" Version="2.4.1" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.4.3" />
     <PackageReference Include="DiffPlex" Version="1.7.0" />