Testing Build will be updated to v1.23.4 on June 20th. This update requires save game changes and only effects users subscribed to testing build.
So if you're on Testing Build, please finish up your current games. :)
With any luck, v1.23.4 save games should work on v1.24 RC, v1.24, and any v1.24 supplemental patches. Cross your fingers. :)