Use isoformat for datetimes

download.py

@@ -92,7 +92,7 @@ def main():
     else:
         log.info(
             "Argument --from-datetime=%r: only datasets that changed since that datetime will be downloaded",
-            args.from_datetime,
+            args.from_datetime.isoformat(),
         )
 
     toc_file_name = "table_of_contents.xml"
@@ -224,7 +224,9 @@ def iter_datasets_to_download(toc_element, from_datetime: Optional[datetime] = N
         last_update = datetime.strptime(last_update_str, "%d.%m.%Y").replace(tzinfo=timezone.utc)
         if last_update >= from_datetime:
             log.debug(
-                "Dataset %r lastUpdate is more recent than %r: it will be downloaded", dataset_code, from_datetime
+                "Dataset %r lastUpdate is more recent than %r: it will be downloaded",
+                dataset_code,
+                from_datetime.isoformat(),
             )
             yield leaf_element