Fix record set update

import_api_app/resources/UpdateRecordSet.py

@@ -69,19 +69,19 @@ class UpdateRecordSet(Resource):
                 requests.get(it_drupal_url, headers=self.headers, auth=self.auth).json()['data']
 
             institutions = drupal_record_set_de['relationships']['field_institution']['data']
-            institution_ids = UpdateRecordSet.get_institution_id_list(institutions)
+            institution_ids = self.get_institution_id_list(institutions)
 
             institutions = \
                 drupal_record_set_de['relationships']['field_resp_institution_access']['data']
-            access_institution_ids = UpdateRecordSet.get_institution_id_list(institutions)
+            access_institution_ids = self.get_institution_id_list(institutions)
 
             institutions = \
                 drupal_record_set_de['relationships']['field_resp_institution_master']['data']
-            master_institutions_ids = UpdateRecordSet.get_institution_id_list(institutions)
+            master_institutions_ids = self.get_institution_id_list(institutions)
 
             institutions = \
                 drupal_record_set_de['relationships']['field_resp_institution_original']['data']
-            original_institution_ids = UpdateRecordSet.get_institution_id_list(institutions)
+            original_institution_ids = self.get_institution_id_list(institutions)
 
             metadata_language_codes = []
             metadata_languages = \