feat: add occurrenceID to preparation

GGBN recommend including it, so here it is.

dataimporter/emu/views/preparation.py

@@ -169,6 +169,7 @@ def transform(self, record: SourceRecord) -> dict:
             "preparationProcess": get_preparation_process(record),
             "preparationDate": gf("EntPreDate"),
             "purpose": get_purpose(record),
+            "occurrenceID": gf("AdmGUIDPreferredValue"),
             "created": emu_date(gf("AdmDateInserted"), gf("AdmTimeInserted")),
             "modified": emu_date(gf("AdmDateModified"), gf("AdmTimeModified")),
         }