VPP-1508 python3 tests: use six.iteritems

This replaces dictionary.iteritems() on Python 2 and dictionary.items() on Python 3.

Change-Id: I58a3ded7d284c59e28d484b0c285aac435bfc229
Signed-off-by: Paul Vinciguerra <pvinci@vinciconsulting.com>

test/remote_test.py

@@ -134,7 +134,7 @@ class RemoteClass(Process):
                isinstance(val, RemoteClassAttr):
                 mutable_args[i] = val.get_remote_value()
         args = tuple(mutable_args)
-        for key, val in kwargs.iteritems():
+        for key, val in six.iteritems(kwargs):
             if isinstance(val, RemoteClass) or \
                isinstance(val, RemoteClassAttr):
                 kwargs[key] = val.get_remote_value()