Fix shebang in command-line scripts

src/ifcbimtester/bimtester.py

@@ -1,3 +1,4 @@
+#!/usr/bin/python3
 # Unix:
 # $ pyinstaller --onefile --clean --icon=icon.ico --add-data "features:features" bimtester.py`
 # Windows:

src/ifcblenderexport/occ_utils.py

@@ -1,3 +1,4 @@
+#!/usr/bin/python3
 ###############################################################################
 #                                                                             #
 # This file is part of IfcOpenShell.                                          #

src/ifcclash/collision.py

@@ -1,3 +1,4 @@
+#!/usr/bin/python3
 # This code is taken from the trimesh project at https://github.com/mikedh/trimesh/blob/master/trimesh/collision.py
 # License MIT https://github.com/mikedh/trimesh/blob/master/LICENSE.md
 

src/ifcclash/ifcclash.py

@@ -1,4 +1,4 @@
-#!python
+#!/usr/bin/python3
 
 import collision
 import ifcopenshell

src/ifccobie/cobie.py

@@ -1,3 +1,4 @@
+#!/usr/bin/python3
 # This can be packaged with `pyinstaller --onefile --clean --icon=icon.ico bimtester.py`
 
 import os

src/ifccsv/ifccsv.py

@@ -1,3 +1,4 @@
+#!/usr/bin/python3
 # This can be packaged with `pyinstaller --onefile --clean --icon=icon.ico ifccsv.py`
 
 import ifcopenshell

src/ifcdiff/ifcdiff.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/python3
 # This can be packaged with `pyinstaller --onefile --clean --icon=icon.ico ifcdiff.py`
 
 import ifcopenshell