[ISSUE #78] add attempt_id in ReceiveMessageRequest (#79)

diff --git a/apache/rocketmq/v2/service.proto b/apache/rocketmq/v2/service.proto
index f662f76..ae534f9 100644
--- a/apache/rocketmq/v2/service.proto
+++ b/apache/rocketmq/v2/service.proto
@@ -97,6 +97,7 @@
   // For message auto renew and clean
   bool auto_renew = 6;
   optional google.protobuf.Duration long_polling_timeout = 7;
+  optional string attempt_id = 8;
 }
 
 message ReceiveMessageResponse {