Allowed 'start_sync_job' to use an 'api' source

The sync API doesn't need an integration id when using an 'api' source.

Author: CraigBryan

jupiterone/client.py

@@ -542,9 +542,11 @@ def start_sync_job(self, instance_id: str = None, sync_mode: str = None, source:
 
         data = {
                "source": source,
-               "integrationInstanceId": instance_id,
                "syncMode": sync_mode
-               }
+        }
+
+        if instance_id is not None:
+            data["integrationInstanceId"] = instance_id
 
         response = self._execute_syncapi_request(endpoint=endpoint, payload=data)
 
@@ -1262,4 +1264,4 @@ def create_update_parameter(self, name: str = None, value: Union[str, int, bool,
         }
 
         response = self._execute_query(UPSERT_PARAMETER, variables=variables)
-        return response
+        return response