Fix wrong feature flag for UDP broadcast test

The UDP broadcast test was using the wrong feature flag. This commit
fixes the feature flag to use the correct one.
This must have slipped through the cracks when I updated the tests to
use rstest.

src/iface/interface/tests/mod.rs

@@ -61,11 +61,15 @@ fn test_new_panic() {
     Interface::new(config, &mut device, Instant::ZERO);
 }
 
+#[cfg(feature = "socket-udp")]
 #[rstest]
-#[cfg(feature = "default")]
-fn test_handle_udp_broadcast(
-    #[values(Medium::Ip, Medium::Ethernet, Medium::Ieee802154)] medium: Medium,
-) {
+#[case::ip(Medium::Ip)]
+#[cfg(feature = "medium-ip")]
+#[case::ethernet(Medium::Ethernet)]
+#[cfg(feature = "medium-ethernet")]
+#[case::ieee802154(Medium::Ieee802154)]
+#[cfg(feature = "medium-ieee802154")]
+fn test_handle_udp_broadcast(#[case] medium: Medium) {
     use crate::socket::udp;
     use crate::wire::IpEndpoint;