PyRevitRunner to honour cpython hash-bang

[tinrobot2000]

Is your feature request related to a problem? Please describe

PyRevitRunner uses the settings IronPython engine even when a script starts with '#! python3'

Describe the solution you'd like

PyRevitRunner uses the Cpython engine in the settings if the script starts with the cpython hash-bang

Describe alternatives you've considered

None, although IronPython3 does work with python3 code, so setting that is a workaround

Additional context

None