Upgrade jsonrpc to 0.18.0 (#9547)

* Upgrade jsonrpc to 0.18.0

I think this says all :P

* 🤦

* Fmt etc

* Fix tests

* Fix tests again...

* Better impl

* Revert "Tell dependabot to ignore jsonrpc-* updates (#9518)"

This reverts commit 6e0cd5587d.

substrate/client/rpc-servers/src/middleware.rs

@@ -73,12 +73,12 @@ impl<M: Metadata> RequestMiddleware<M> for RpcMiddleware {
 	fn on_request<F, X>(&self, request: Request, meta: M, next: F) -> Either<FutureResponse, X>
 	where
 		F: Fn(Request, M) -> X + Send + Sync,
-		X: Future<Item = Option<Response>, Error = ()> + Send + 'static,
+		X: Future<Output = Option<Response>> + Send + 'static,
 	{
 		if let Some(ref rpc_calls) = self.metrics.rpc_calls {
 			rpc_calls.with_label_values(&[self.transport_label.as_str()]).inc();
 		}
 
-		Either::B(next(request, meta))
+		Either::Right(next(request, meta))
 	}
 }