tests: 3.x syntax compat for tests/data/stubs/

tests/data/stubs/stub-lxc-info.py

@@ -1,4 +1,4 @@
 #!/usr/bin/env python
 # Mainly for use in stubconnections/kubectl.yml
 
-print 'PID: 1'
+print('PID: 1')

tests/data/stubs/stub-lxc.py

@@ -5,7 +5,7 @@ import os
 
 # setns.py fetching leader PID.
 if sys.argv[1] == 'info':
-    print 'Pid: 1'
+    print('Pid: 1')
     sys.exit(0)
 
 os.environ['ORIGINAL_ARGV'] = repr(sys.argv)