Hotfix add array wrapper for solr update request

This reverts commit f07ccb6a.

data_harvesting/indexer/indexer.py

@@ -776,7 +776,7 @@ def extract_ids(data: List[dict], pattern: str = '://ror.org') -> List[str]:
     """Extract all identifiers that match a certain pattern"""
     id_list = []
     for entry in data:
-        _id = entry.get('@id', '')
+        _id = str(entry.get('@id', ''))
         if pattern in _id:
             id_list.append(_id)
     return list(set(id_list))