Fix missing Python psutil module
    
    In most logs (e.g.
    https://kojipkgs.fedoraproject.org//work/tasks/9788/66839788/build.log)
    you can find this output:
    
    ```
    llvm-lit: /builddir/build/BUILD/llvm-12.0.0.src/x86_64-redhat-linux-gnu/utils/lit/tests/lit.cfg:79: warning: Setting a timeout per test not supported. Requires the Python psutil module but it could not be found. Try installing it via pip or via your operating system's package manager. Some tests will be skipped and the --timeout command line argument will not work.
    ```