fix(test): only listen on 127.0.0.1 for ephemeral swarm

This resolves an issue where our tests were depending on the number of network interfaces available on the local machine.

Related #4110.

Pull-Request: #4122.


  
Co-Authored-By: Thomas Eizinger <thomas@eizinger.io>

swarm-test/src/lib.rs

@@ -312,7 +312,7 @@ where
         self.add_external_address(memory_multiaddr.clone());
 
         let tcp_addr_listener_id = self
-            .listen_on("/ip4/0.0.0.0/tcp/0".parse().unwrap())
+            .listen_on("/ip4/127.0.0.1/tcp/0".parse().unwrap())
             .unwrap();
 
         let tcp_multiaddr = self