tests: python3 changes for span and aclplugin test

Type: fix
Change-Id: Ia9f74f951f831cc5c9b5af863db1bb3f7a1a81ff
Signed-off-by: snaramre <snaramre@cisco.com>
diff --git a/test/test_span.py b/test/test_span.py
index c67bc7b..3b31f62 100644
--- a/test/test_span.py
+++ b/test/test_span.py
@@ -144,7 +144,7 @@
 
         for i in range(0, self.pkts_per_burst):
             payload = "span test"
-            size = packet_sizes[(i / 2) % len(packet_sizes)]
+            size = packet_sizes[int((i / 2) % len(packet_sizes))]
             p = (Ether(src=src_if.local_mac, dst=dst_mac) /
                  IP(src=src_if.remote_ip4, dst=dst_if.remote_ip4) /
                  UDP(sport=10000 + src_if.sw_if_index * 1000 + i, dport=1234) /