LGTM distribution configuration

I have an app written in C++ using Qt that I’d like to scan with LGTM. Unfortunately, while I’m requiring Qt 5.15 or higher, whatever distribution used under the hood doesn’t provide a new enough version of Qt. Therefore, I’d like to be able to either update the Qt packages or use an upgraded distribution altogether.

Does anybody have any information on how to do this?

Also, my IDE auto-generated a CMakeLists.txt that has CMake version 3.14 required. This is not a particular requirement, but the LGTM error message shows me that LGTM has only version 3.13.4, which matches the Debian Buster version.