rrs/tools: run all tools scripts with python3

These scripts should all now be run under python 3, so update the
shebangs accordingly.

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>

rrs/tools/rrs_distros.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 # Update current distro information for recipes.
 #

rrs/tools/rrs_maintainer_history.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 # Standalone script which rebuilds the history of maintainership
 #

rrs/tools/rrs_upgrade_history.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 # Standalone script which rebuilds the history of all the upgrades.
 #

rrs/tools/rrs_upstream_email.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 # -*- coding: utf-8 -*-
 
 # Send email to maintainers about the current status of the recipes.

rrs/tools/rrs_upstream_history.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 # Get upstream information for recipes.
 #