support for external_id on intervals.icu

rowers/integrations/intervals.py

@@ -18,6 +18,7 @@ from uuid import uuid4
 from django.utils import timezone
 from datetime import timedelta
 import rowers.dataprep as dataprep
+from rowers.opaque import encoder
 
 from rowsandall_app.settings import (
     INTERVALS_CLIENT_ID, INTERVALS_REDIRECT_URI, INTERVALS_CLIENT_SECRET, SITE_URL
@@ -171,6 +172,7 @@ class IntervalsIntegration(SyncIntegration):
         params = {
             'name': workout.name,
             'description': workout.notes,
+            'external_id': encoder.encode_hex(workout.id),
             }