Call to python3 for stand-alone scripts

Needed since Debian & FreeBSD both move away from keeping a synlink to `python`.

build_files/package_spec/build_archive.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 # <pep8 compliant>
 

doc/manpage/blender.1.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 # ##### BEGIN GPL LICENSE BLOCK #####
 #

release/bin/blender-thumbnailer.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 # ##### BEGIN GPL LICENSE BLOCK #####
 #

release/datafiles/ctodata.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 # -*- coding: utf-8 -*-
 
 # ***** BEGIN GPL LICENSE BLOCK *****

release/scripts/modules/blend_render_info.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 # ##### BEGIN GPL LICENSE BLOCK #####
 #