[BUG]: imager does not display Ubuntu in any dropdown

### What happened? I have just booted a brand new RPI 5 with PI OS pre-installed on an SD card. I need to install Ubuntu onto a Usb 3 but when I run rpi_imager, Ubuntu is not visible on any of the OS drop downs. How can I get Ubuntu loaded? I do now own a Windows or Apple machines. Only Android and the Pi. ### Version 2.0.9 (Default) ### What host operating system were you using? Other Linux environment ### Host OS Version Latest PI OS ### Selected OS Trying to find Ubuntu ### Which Raspberry Pi Device are you using? Raspberry Pi 5, 500, and Compute Modules 5 ### What kind of storage device are you using? microSD Card in an internal reader ### OS Customisation - [ ] Yes, I was using OS Customisation when the bug occurred. ### Relevant log output ```shell ```