Update python -> python3 in scripts.

Author: davexparker

prism/etc/scripts/prism-auto

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 # The prism-auto script automatically executes PRISM on one or more
 # models/properties, for the purposes of benchmarking or testing.

prism/etc/scripts/prism-filler.py

@@ -1,4 +1,4 @@
-#! /usr/bin/env python
+#! /usr/bin/env python3
 # coding=utf-8
 
 # run without arguments for usage info

prism/etc/scripts/prism-log-extract

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 # The prism-log-extract script extracts and collates info from a
 # collection of PRISM log files.

prism/etc/scripts/prism-pareto.py

@@ -1,4 +1,4 @@
-#! /usr/bin/env python
+#! /usr/bin/env python3
 # coding=utf-8
 
 # run without arguments for usage info