FIX: Use linkahead module for import of private functions

unittests/test_cfood.py

@@ -32,7 +32,7 @@ from caosadvancedtools.cfood import (AbstractCFood, AbstractFileCFood, CMeal,
                                      get_entity_for_path)
 from caosadvancedtools.crawler import FileCrawler
 from caosadvancedtools.example_cfood import ExampleCFood
-from caosdb.common.models import _parse_single_xml_element
+from linkahead.common.models import _parse_single_xml_element
 from lxml import etree
 from datetime import datetime, timezone