fix: pandas dot notation does not add a column

pandas-dev/pandas#7175

Author: itsjohnward

api/client/gro_client.py

@@ -907,7 +907,7 @@ def add_points_to_df(self, index, data_series, data_points, *args):
         # get_data_points response doesn't include the
         # source_id. We add it as a column, in case we have
         # several selections series which differ only by source id.
-        tmp.source_id = data_series["source_id"]
+        tmp["source_id"] = data_series["source_id"]
         # tmp should always have end_date/start_date/reporting_date as columns if not empty
         tmp.end_date = pandas.to_datetime(tmp.end_date)
         tmp.start_date = pandas.to_datetime(tmp.start_date)