we now extend the history instead of replacing it

src/toargridding/metadata.py

@@ -216,10 +216,9 @@ def get_global_attributes(metadata: Metadata) -> dict:
     if metadata.contributors_metadata_field is None:
         raise ValueError("metadata.contributors_metadata_field must be set before calling get_global_attributes")
 
+    history = f"{date_created}: File created by toargridding package using data from toar-analysis service."
     if metadata.history is not None:
-        history = metadata.history
-    else:
-        history = f"{date_created}: File created by toargridding package using data from toar-analysis service"
+        history += " " + metadata.history
     dynamic_cf_attributes = {
         "id": metadata.get_id(),
         "title": metadata.get_title(),