Bump Verify.Xunit from 13.3.1 to 14.7.0 in /Rx.NET/Source

Bumps [Verify.Xunit](https://github.com/VerifyTests/Verify) from 13.3.1 to 14.7.0.
- [Release notes](https://github.com/VerifyTests/Verify/releases)
- [Commits](https://github.com/VerifyTests/Verify/compare/13.3.1...14.7.0)

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

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

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="17.0.0" />
-    <PackageReference Include="Verify.Xunit" Version="13.3.1" />
+    <PackageReference Include="Verify.Xunit" Version="14.7.0" />
     <PackageReference Include="xunit" Version="2.4.1" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.4.3" />
     <PackageReference Include="DiffPlex" Version="1.7.0" />