convert shebang lines: python -> python3
diff --git a/Tools/scripts/which.py b/Tools/scripts/which.py
index a9f4907..4fc37a0 100755
--- a/Tools/scripts/which.py
+++ b/Tools/scripts/which.py
@@ -1,4 +1,4 @@
-#! /usr/bin/env python
+#! /usr/bin/env python3
 
 # Variant of "which".
 # On stderr, near and total misses are reported.