Update checkcolor.py hashbang to Python 3 am: ee59816895 am: 8b7e6cc073 am: 4f8c37e10d am: 383d3e0bf1

Original change: https://android-review.googlesource.com/c/platform/prebuilts/checkcolor/+/1971582

Change-Id: I01a621d1fc21f4e6759f15f9329b11838ec882c1
diff --git a/checkcolor.py b/checkcolor.py
index c64495e..f1033ad 100755
--- a/checkcolor.py
+++ b/checkcolor.py
@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python3
 
 #
 # Copyright 2017, The Android Open Source Project