FVP Python Version conflicts

[ReinhardKeil]

AVH FVP requires Python version 3.9. It should be explored if the version can be updated and a version compatibility can be published.

Background is that Vela and other tools require newer Python versions and the old version in AVH FVP frequently creates conflicts (for example when the PYTHONPATH is set).

See also #137

[jkrech]

Achieving compatibility across python 3 with a yet to be defined 3.x minimum version is targeted for the FVP models version 11.30.??