Python3 tests: Fix asserts.

Use assert(Not)Equal()
Use assert{Greater,Less}[Equal]

Change-Id: I7c14570b8dce463ee13a67e9c1f10beb1a0308a8
Signed-off-by: Paul Vinciguerra <pvinci@vinciconsulting.com>
diff --git a/test/test_ip6.py b/test/test_ip6.py
index 95f9229..33194eb 100644
--- a/test/test_ip6.py
+++ b/test/test_ip6.py
@@ -1920,8 +1920,8 @@
         # but not equal to the number sent, since some were policed
         #
         rx = self.pg1._get_capture(1)
-        self.assertTrue(len(rx) > 0)
-        self.assertTrue(len(rx) < len(pkts))
+        self.assertGreater(len(rx), 0)
+        self.assertLess(len(rx), len(pkts))
 
         #
         # remove the poilcer. back to full rx