Update questaformal.py

[durmazh997]

Because of the seperate if conditions, args gets the empty list value when file type endswith -87 or -93.

[olofk]

Oops! Thanks for catching that. Before merging this, I will need an update to the tests as well. You can run the test suite locally by running tox from the repo root. Set the GOLDEN_RUN environmnent variable to get some help with updating the reference files. More info here https://edalize.readthedocs.io/en/latest/dev/tests.html and let me know if you need any help.