adding data_valid parameter although it is not a well-defined.

geomagio/processing/magproc.py

@@ -137,6 +137,7 @@ def write_cal_file(
             endtime=endtime,
             station=observatory,
             status="reviewed",
+            data_valid=True,
         )
         metadata = factory.get_metadata(query=query)
         # convert returned metadata.metadata into Reading objects