Bump Verify.Xunit from 6.22.1 to 6.23.0 in /Rx.NET/Source
Bumps [Verify.Xunit](https://github.com/VerifyTests/Verify) from 6.22.1 to 6.23.0.
- [Release notes](https://github.com/VerifyTests/Verify/releases)
- [Commits](https://github.com/VerifyTests/Verify/commits)
Signed-off-by: dependabot-preview[bot] <[email protected]>