add priority config for fcm messages

firebase/fcm.go

@@ -76,11 +76,17 @@ func sendNotification(app FBSender, token string, data *mixmessages.Notification
 	ctx := context.Background()
 	message := &messaging.Message{
 		Notification: nil, // This must remain nil for the data to go to android apps in background
+		Android: &messaging.AndroidConfig{
+			Priority: "high",
+		},
 		Data: map[string]string{
 			"MessageHash":         base64.StdEncoding.EncodeToString(data.MessageHash),
 			"IdentityFingerprint": base64.StdEncoding.EncodeToString(data.IdentityFP),
 		},
 		APNS: &messaging.APNSConfig{ // APNS is apple's native notification service, this is ios specific config
+			Headers: map[string]string{
+				"apns-priority": "5",
+			},
 			Payload: &messaging.APNSPayload{
 				Aps: &messaging.Aps{
 					ContentAvailable: true,