fix header time develop-humble (#239)

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# PR Details
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develop-humble mirror PR of: 
#231
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carma-messenger-core/traffic_incident/src/traffic_incident_worker.cpp

@@ -35,7 +35,7 @@ carma_v2x_msgs::msg::MobilityOperation TrafficIncidentWorker::mobilityMessageGen
 {
   carma_v2x_msgs::msg::MobilityOperation traffic_mobility_msg;
 
-  traffic_mobility_msg.m_header.timestamp = pinpoint_msg.header.stamp.sec * 1000;
+  traffic_mobility_msg.m_header.timestamp = rclcpp::Time(pinpoint_msg.header.stamp).nanoseconds() / 1e6;
   traffic_mobility_msg.m_header.sender_id = sender_id_;
 
   traffic_mobility_msg.strategy = USE_CASE_NAME_;
@@ -102,4 +102,4 @@ gps_msgs::msg::GPSFix TrafficIncidentWorker::getPinPoint() { return this->pinpoi
 
 double TrafficIncidentWorker::getAdvisorySpeed() { return this->advisory_speed_; }
 
-}  // namespace traffic
+}  // namespace traffic