Don't specify peer port

Using a port of 0 and letting the OS choose for us means that we can run multiple peers locally

src/lib.rs

@@ -20,7 +20,7 @@ pub struct AppSettings {
     source: Source,
 
     /// The port the app should listen for connections on
-    #[arg(short, long, default_value = "25565")]
+    #[arg(short, long, default_value = "0")]
     port: u16,
 }