According to their info:
Regarding the PySide/compiler version, you can check the CI logs: Where you can select any log raw from those configurations and get this:
agent:2021/04/13 16:01:52 build.go:379: -- The C compiler identification is GNU 8.3.1 agent:2021/04/13 16:01:53 build.go:379: -- The CXX compiler identification is GNU 8.3.1