DEMO regression test using illegal constraint combinations #4056
Description
The following error occurs when running the new DEMO file
=========================== short test summary info ============================
FAILED tests/regression/test_process_input_files.py::test_input_file[low_aspect_ratio_DEMO] - RuntimeError: An error occured while running PROCESS: Iteration variable 60 (TF current per turn, c_tf_turn) cannot be used with the TF coil integer turn model (i_tf_turns_integer == 1) as it is a calculated output instead for this model. However, the maximum current per turn can be constrained with constraint 77.
============= 1 failed, 7 passed, 28 warnings in 96.17s (0:01:36) ==============
following the merge of #4034.