More python updates

Followup to #13931

buildroot/share/scripts/createTemperatureLookupMarlin.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python
 """Thermistor Value Lookup Table Generator
 
 Generates lookup to temperature values for use in a microcontroller in C format based on:

buildroot/share/scripts/g29_auto.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python
 
 # This file is for preprocessing gcode and the new G29 Autobedleveling from Marlin
 # It will analyse the first 2 Layer and return the maximum size for this part