If you’ve been downloading Raspbian from the Raspberry Pi Foundation, the July 10 version is available here: https://www.raspberrypi.org/downloads/raspbian/
This one is based on Debian “Buster” and includes support for the Raspberry Pi 4.
For those who like the KSU Workshop version, I’ve built one based on the new release. It is available here: https://ccse.kennesaw.edu/outreach/raspberrypi/resources.php