added shebang to run python scripts

util/compare_gnu_result.py

@@ -1,4 +1,4 @@
-#! /usr/bin/python
+#!/usr/bin/env python3
 
 """
 Compare the current results to the last results gathered from the main branch to highlight

util/size-experiment.py

@@ -1,3 +1,4 @@
+#!/usr/bin/env python3
 # spell-checker:ignore debuginfo
 import subprocess
 from itertools import product