convert shebang lines: python -> python3
diff --git a/Tools/scripts/byteyears.py b/Tools/scripts/byteyears.py
index f486d26..490b37f 100755
--- a/Tools/scripts/byteyears.py
+++ b/Tools/scripts/byteyears.py
@@ -1,4 +1,4 @@
-#! /usr/bin/env python
+#! /usr/bin/env python3
 
 # Print the product of age and size of each file, in suitable units.
 #