This issue seems to be resolved. Ventura apparently changed the warning dialog which appears when opening an unsigned application, and added a second layer of confirmation too.
The app can be opened by going to System Preferences --> Privacy and Security, then clicking "Open Anyway". The OS will give a second error, but returning to System Preferences and following the same process again will force it to open.
This issue seems to be resolved. Ventura apparently changed the warning dialog which appears when opening an unsigned application, and added a second layer of confirmation too.
The app can be opened by going to System Preferences --> Privacy and Security, then clicking "Open Anyway". The OS will give a second error, but returning to System Preferences and following the same process again will force it to open.