fix: add missing use<> for wasm_browser (#3411)

## Description

The migration to edition 2024 missed signatures gated with
`cfg(wasm_browser)`. Spotted while upgrading iroh-gossip to iroh@main.

## Breaking Changes

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including how to migrate older code. -->

## Notes & open questions

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## Change checklist
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- [x] Self-review.

Author: Frando

iroh/src/endpoint.rs

@@ -937,7 +937,7 @@ impl Endpoint {
     /// with a [`NodeAddr`] that only contains a relay URL, but no direct addresses,
     /// as there are no APIs for directly using sockets in browsers.
     #[cfg(wasm_browser)]
-    pub fn node_addr(&self) -> impl n0_watcher::Watcher<Value = Option<NodeAddr>> {
+    pub fn node_addr(&self) -> impl n0_watcher::Watcher<Value = Option<NodeAddr>> + use<> {
         // In browsers, there will never be any direct addresses, so we wait
         // for the home relay instead. This makes the `NodeAddr` have *some* way
         // of connecting to us.