proxyd: Add nonce to sender-based rate limit

.changeset/tame-lions-build.md

+---
+'@eth-optimism/proxyd': minor
+---
+
+Include nonce in sender rate limit

proxyd/server.go

@@ -631,7 +631,7 @@ func (s *Server) rateLimitSender(ctx context.Context, req *RPCReq) error {
 		return ErrInvalidParams(err.Error())
 	}
 
-	ok, err := s.senderLim.Take(ctx, msg.From().Hex())
+	ok, err := s.senderLim.Take(ctx, fmt.Sprintf("%s:%d", msg.From().Hex(), tx.Nonce()))
 	if err != nil {
 		log.Error("error taking from sender limiter", "err", err, "req_id", GetReqID(ctx))
 		return ErrInternal