tests: fix UDP multicast transport tests with IPv6

A valid scope id is always required on the multicast address

Change-Id: Ic676fcde0ee50daf75eb38c137e3cb917f43699f
diff --git a/tests/daemon/face/test-netif.cpp b/tests/daemon/face/test-netif.cpp
index 1a2752b..68b66cd 100644
--- a/tests/daemon/face/test-netif.cpp
+++ b/tests/daemon/face/test-netif.cpp
@@ -28,6 +28,9 @@
 
 namespace nfd::tests {
 
+using ndn::net::NetworkInterface;
+using ndn::net::NetworkMonitor;
+
 std::vector<shared_ptr<const NetworkInterface>>
 enumerateNetworkInterfaces(NetworkMonitor& netmon)
 {