Set created & updated timestamps of names to datetime values

* it looks like these fields in the name entry records got turned into
  strings at some point in our TISS sync, causing issues during
  marshmallow serialization

invenio_config_tuw/tiss/tasks.py

@@ -151,6 +151,11 @@ def sync_names_from_tiss() -> dict:
 
                     # if we found a match via ORCID, we update it according to the TISS data
                     name = svc.read(identity=system_identity, id_=name_voc_id)
+
+                    # reset created & updated timestamps to their datetime/non-string
+                    # form, to avoid breakage in the serialization
+                    name._obj["updated"] = name._obj.updated
+                    name._obj["created"] = name._obj.created
                     new_name_data = update_name_data(
                         name.data, employee, tuw_ror_aliases
                     )