Arch: ImportOBJ.py LGTM fixes [skip ci]
Arch: ImportOBJ.py LGTM fixes [skip ci]

Fixes recommended via LGTM report
Fat-Zer/FreeCAD_sf_master,Fat-Zer/FreeCAD_sf_master,Fat-Zer/FreeCAD_sf_master,Fat-Zer/FreeCAD_sf_master,Fat-Zer/FreeCAD_sf_master