check_whence.py: Use a more portable shebang.

Some systems do not have /usr/bin/python3, e.g. Guix System and NixOS.
Look python3 from PATH.

Signed-off-by: Maxim Cournoyer <maxim.cournoyer@gmail.com>

diff --git a/check_whence.py b/check_whence.py
index 42480892aab5bd8008f6105d5ee493fa12bee280..357c1311cf5a038da69a8acb2015d377f25fdea4 100755 (executable)
--- a/check_whence.py
+++ b/check_whence.py
@@ -1,4 +1,4 @@
-#!/usr/bin/python3
+#!/usr/bin/env python3
 
 import os, re, stat, sys
 from io import open