Add conda env to path if missing

[daklauss]

Especially on windows, it is very likely, that the current conda environment ist not added to the path variable. In this case, if cadet python is not able to detect the instance of cadet, two new path entries are added to the path within execution.

 dll_paths = [
                str(Path(sys.prefix) / 'Library' / 'bin'),
                str(Path(sys.prefix) / 'bin'),
]