python3: itervalues no longer exists

Fortunately, the peers dict is small, so we can just use values()

lib/chutney/Traffic.py

@@ -356,7 +356,7 @@ class TrafficTester():
         return self.get_by_ptype(Peer.SOURCE)
 
     def get_by_ptype(self, ptype):
-        return filter(lambda p: p.type == ptype, self.peers.itervalues())
+        return list(filter(lambda p: p.type == ptype, self.peers.values()))
 
     def add(self, peer):
         self.peers[peer.fd()] = peer