fix: fix Tkinter bug when missing tempfile

[NeirdaP]

On MacOS (didn't test on any other OS), when launching renardo with the foxdot editor, there where this error indicating a temp file was missing.

At first, I thought this was benign but then I realized it created a strange comportement with Tkinter, where any click on the top menu bar or any right-click on the editor would make everything freeze and force the user to force-quit the program.

Just for a quick test, I created the missing file (leaving it empty 'cause I didn't know his purpose) and it seemed I don't have any more GUI issue :)