use python3 instead of python in tests/python/Makefile and tests/update/check_update.py

Author: kulaginm

Diff for: tests/python/Makefile

@@ -1,6 +1,6 @@
 partitioning_tests:
 ifneq ($(CASE),)
-	python partitioning_test.py Tests.$(CASE)
+	python3 partitioning_test.py Tests.$(CASE)
 else
-	python partitioning_test.py
+	python3 partitioning_test.py
 endif

Diff for: tests/update/check_update.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 #coding: utf-8
 
 import shutil