fix: relax Deserialize bound in ingress call to support all Error types

The upstream Deserialize trait now has an associated Error type. Relax the
ingress `call()` and `decode_response()` bounds from requiring
`Error = serde_json::Error` to accepting any error type convertible to
RequestError via `From`.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: robertream

src/ingress.rs

@@ -437,15 +437,17 @@ impl<Res> Request<Res> {
     pub async fn call<E>(self, executor: &E) -> Result<Res, RequestError>
     where
         E: executor::Executor,
-        Res: Deserialize<Error = serde_json::Error>,
+        Res: Deserialize,
+        RequestError: From<Res::Error>,
     {
         decode_response(executor.execute(self.request?).await?)
     }
 }
 
 fn decode_response<Res>(response: executor::HttpResponse) -> Result<Res, RequestError>
 where
-    Res: Deserialize<Error = serde_json::Error>,
+    Res: Deserialize,
+    RequestError: From<Res::Error>,
 {
     if response.status < 200 || response.status > 299 {
         let status = response.status;